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  • 1.
    Abdi-Jalebi, Mojtaba
    et al.
    Univ Cambridge, Dept Phys, Cavendish Lab, JJ Thomson Ave, Cambridge, England.
    Pazoki, Meysam
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Philippe, Bertrand
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Dar, M. Ibrahim
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photon & Interfaces, Lausanne, Switzerland.
    Alsari, Mejd
    Univ Cambridge, Dept Phys, Cavendish Lab, JJ Thomson Ave, Cambridge, England.
    Sadhanala, Aditya
    Univ Cambridge, Dept Phys, Cavendish Lab, JJ Thomson Ave, Cambridge, England.
    Diyitini, Giorgio
    Univ Cambridge, Dept Mat Sci & Met, Charles Babbage Rd, Cambridge, England.
    Imani, Roghayeh
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Lilliu, Samuele
    Univ Sheffield, Dept Phys & Astron, Sheffield, S Yorkshire, England; UAE Ctr Crystallog, Dubai, U Arab Emirates.
    Kullgren, Jolla
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Gratzel, Michael
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photon & Interfaces, Lausanne, Switzerland.
    Friend, Richard H.
    Univ Cambridge, Dept Phys, Cavendish Lab, JJ Thomson Ave, Cambridge, England.
    Dedoping of Lead Halide Perovskites Incorporating Monovalent Cations2018In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 12, no 7, p. 7301-7311Article in journal (Refereed)
    Abstract [en]

    We report significant improvements in the optoelectronic properties of lead halide perovskites with the addition of monovalent ions with ionic radii close to Pb2+. We investigate the chemical distribution and electronic structure of solution processed CH3NH3PbI3 perovskite structures containing Na+, Cu+, and Ag+, which are lower valence metal ions than Pb2+ but have similar ionic radii. Synchrotron X-ray diffraction reveals a pronounced shift in the main perovskite peaks for the monovalent cation-based films, suggesting incorporation of these cations into the perovskite lattice as well as a preferential crystal growth in Ag+ containing perovskite structures. Furthermore, the synchrotron X-ray photoelectron measurements show a significant change in the valence band position for Cu- and Ag-doped films, although the perovskite bandgap remains the same, indicating a shift in the Fermi level position toward the middle of the bandgap. Such a shift infers that incorporation of these monovalent cations dedope the n-type perovskite films when formed without added cations. This dedoping effect leads to cleaner bandgaps as reflected by the lower energetic disorder in the monovalent cation-doped perovskite thin films as compared to pristine films. We also find that in contrast to Ag+ and Cu+, Na+ locates mainly at the grain boundaries and surfaces. Our theoretical calculations confirm the observed shifts in X-ray diffraction peaks and Fermi level as well as absence of intrabandgap states upon energetically favorable doping of perovskite lattice by the monovalent cations. We also model a significant change in the local structure, chemical bonding of metal-halide, and the electronic structure in the doped perovskites. In summary, our work highlights the local chemistry and influence of monovalent cation dopants on crystallization and the electronic structure in the doped perovskite thin films.

  • 2.
    Abou-Hamad, Edy
    et al.
    Universite Montpellier 2, France.
    Kim, Y.
    University of Pennsylvania, Philadelphia.
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Boesch, D.
    University of California at Berkeley, and Materials Sciences Division, Lawrence Berkeley National Laboratory.
    Aloni, S.
    University of California at Berkeley, and Materials Sciences Division, Lawrence Berkeley National Laboratory.
    Zettl, Alex
    University of California at Berkeley, and Materials Sciences Division, Lawrence Berkeley National Laboratory.
    Rubio, Angelo
    Universidad del Pas Vasco UPV/EHU.
    Luzzi, David E.
    University of Pennsylvania, Philadelphia.
    Goze-Bac, Christophe
    CNRS Universit Montpellier 2.
    Molecular dynamics and phase transition in one-dimensional crystal of C60 encapsulated inside single wall carbon nanotubes2009In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 3, no 12, p. 3878-3883Article in journal (Refereed)
    Abstract [en]

    One-dimensional crystals of 25% 13C-enriched C60 encapsulated inside highly magnetically purified SWNTs were investigated by following the temperature dependence of the 13C NMR line shapes and the relaxation rates from 300 K down to 5 K. High-resolution MAS techniques reveal that 32% of the encapsulated molecules, so-called the C60α, are blocked at room temperature and 68%, labeled C60β, are shown to reversly undergo molecular reorientational dynamics. Contrary to previous NMR studies, spin−lattice relaxation time reveals a phase transition at 100 K associated with the changes in the nature of the C60β dynamics. Above the transition, the C60β exhibits continuous rotational diffusion; below the transition, C60β executes uniaxial hindered rotations most likely along the nanotubes axis and freeze out below 25 K. The associated activation energies of these two dynamical regimes are measured to be 6 times lower than in fcc-C60, suggesting a quiet smooth orientational dependence of the interaction between C60β molecules and the inner surface of the nanotubes.

  • 3.
    Anasori, Babak
    et al.
    Drexel University, PA 19104 USA; Drexel University, PA 19104 USA.
    Xie, Yu
    Oak Ridge National Lab, TN 37831 USA.
    Beidaghi, Majid
    Drexel University, PA 19104 USA; Drexel University, PA 19104 USA.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hosler, Brian C.
    Drexel University, PA 19104 USA.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Kent, Paul R. C.
    Oak Ridge National Lab, TN 37831 USA; Oak Ridge National Lab, TN 37831 USA.
    Gogotsi, Yury
    Drexel University, PA 19104 USA; Drexel University, PA 19104 USA.
    Barsoum, Michel W.
    Drexel University, PA 19104 USA.
    Two-Dimensional, Ordered, Double Transition Metals Carbides (MXenes)2015In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 9, no 10, p. 9507-9516Article in journal (Refereed)
    Abstract [en]

    The higher the chemical diversity and structural complexity of two-dimensional (2D) materials, the higher the likelihood they possess unique and useful properties. Herein, density functional theory (DFT) is used to predict the existence of two new families of 2D ordered, carbides (MXenes), MM-2 C-2 and MM-2 C-2(3), where M and M are two different early transition metals. In these solids, M layers sandwich M" carbide layers. By synthesizing Mo2TiC2Tx, Mo2Ti2C3Tx, and Cr2TiC2Tx (where T is a surface termination), we validated the DFT predictions. Since the Mo and Cr atoms are on the outside, they control the 2D flakes chemical and electrochemical properties. The latter was proven by showing quite different electrochemical behavior of Mo2TiC2Tx and Ti3C2Tx. This work further expands the family of 2D materials, offering additional choices of structures, chemistries, and ultimately useful properties.

  • 4.
    Andrén, Daniel
    et al.
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Shao, Lei
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Länk, Nils Odebo
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Acimovic, Srdjan S.
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Johansson, Peter
    Örebro University, School of Science and Technology. Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Käll, Mikael
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Probing Photothermal Effects on Optically Trapped Gold Nanorods by Simultaneous Plasmon Spectroscopy and Brownian Dynamics Analysis2017In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 11, no 10, p. 10053-10061Article in journal (Refereed)
    Abstract [en]

    Plasmonic gold nanorods are prime candidates for a variety of biomedical, spectroscopy, data storage, and sensing applications. It was recently shown that gold nanorods optically trapped by a focused circularly polarized laser beam can function as extremely efficient nanoscopic rotary motors. The system holds promise for-applications ranging from nanofluidic flow control and nanorobotics to biomolecular actuation and analysis. However, to fully exploit this potential, one needs to be able to control and understand heating effects associated with laser trapping. We investigated photothermal heating of individual rotating gold nanorods by simultaneously probing their localized surface plasmon resonance spectrum and rotational Brownian dynamics over extended periods of time. The data reveal an extremely slow nanoparticle reshaping process, involving migration of the order of a few hundred atoms per minute, for moderate laser powers and a trapping wavelength close to plasmon resonance. The plasmon spectroscopy and Brownian analysis allows for separate temperature estimates based on the refractive index and the viscosity of the water surrounding a trapped nanorod. We show that both measurements yield similar effective temperatures, which correspond to the actual temperature at a distance of the order 10-15 nm from the particle surface. Our results shed light on photothermal processes on the nanoscale and will be useful in evaluating the applicability and performance of nanorod motors and optically heated nanoparticles for a variety of applications.

  • 5.
    Ansari, Farhan
    et al.
    Stanford Univ, Dept Mat Sci & Engn, Stanford, CA 94305 USA..
    Ding, Yichuan
    Stanford Univ, Dept Mat Sci & Engn, Stanford, CA 94305 USA..
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Dauskardt, Reinhold H.
    Stanford Univ, Dept Mat Sci & Engn, Stanford, CA 94305 USA..
    Toward Sustainable Multifunctional Coatings Containing Nanocellulose in a Hybrid Glass Matrix2018In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 12, no 6, p. 5495-5503Article in journal (Refereed)
    Abstract [en]

    We report on a sustainable route to protective nanocomposite coatings, where one of the components, nanocellulose fibrils, is derived from trees and the glass matrix is an inexpensive sol-gel organic-inorganic hybrid of zirconium alkoxide and an epoxy-functionalized silane. The hydrophilic nature of the colloidal nanocellulose fibrils is exploited to obtain a homogeneous one-pot suspension of the nanocellulose in the aqueous sol-gel matrix precursors solution. The mixture is then sprayed to form nano composite coatings of a well-dispersed, random in-plane nano cellulose fibril network in a continuous organic inorganic glass matrix phase. The nanocellulose incorporation in the sol-gel matrix resulted in nanostructured composites with marked effects on salient coating properties including optical transmittance, hardness, fracture energy, and water contact angle. The particular role of the nanocellulose fibrils on coating fracture properties, important for coating reliability, was analyzed and discussed in terms of fibril morphology, molecular matrix, and nanocellulose/matrix interactions.

  • 6.
    Barbero, David R.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Boulanger, Nicolas
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ultralow Percolation Threshold in Nanoconfined Domains2017In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 11, no 10, p. 9906-9913Article in journal (Refereed)
    Abstract [en]

    Self-assembled percolated networks play an important role in many advanced electronic materials and devices. In nanocarbon composites, decreasing the percolation threshold phi(c) is of paramount importance to reduce nanotube bundling, minimize material resources and costs, and enhance charge transport. Here we demonstrate that three-dimensional nanoconfinement in single-wall carbon nanotube/polymer nanocomposites produces a strong reduction in phi(c) reaching the lowest value ever reported in this system of phi(c) approximate to 1.8 X 10(-5) wt % and 4-5 orders of magnitude lower than the theoretical statistical percolation threshold oh phi(stat) Moreover, a change in network resistivity and electrical conduction was observed with increased confinement, and a simple resistive model is used to accurately estimate the difference in is in the confined networks. These results are explained in terms of networks' size, confinement, and tube orientation as determined by atomic force microscopy, electrical conductivity measurements, and polarized Raman spectroscopy. Our findings provide important insight into nanoscale percolated networks and should find application in electronic nanocomposites and devices.

  • 7.
    Belkin, Maxim
    et al.
    University of Illinois, IL 61801 USA.
    Chao, Shu-Han
    University of Illinois, IL 61801 USA.
    Jonsson, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering. Delft University of Technology, Netherlands.
    Dekker, Cees
    Delft University of Technology, Netherlands.
    Aksimentiev, Aleksei
    University of Illinois, IL 61801 USA.
    Plasmonic Nanopores for Trapping, Controlling Displacement, and Sequencing of DNA2015In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 9, no 11, p. 10598-10611Article in journal (Refereed)
    Abstract [en]

    With the aim of developing a DNA sequencing methodology, we theoretically examine the feasibility of using nanoplasmonics to control the translocation of a DNA molecule through a solid-state nanopore and to read off sequence information using surface-enhanced Raman spectroscopy. Using molecular dynamics simulations, we show that high-intensity optical hot spots produced by a metallic nanostructure can arrest DNA translocation through a solid-state nanopore, thus providing a physical knob for controlling the DNA speed. Switching the plasmonic field on and off can displace the DNA molecule in discrete steps, sequentially exposing neighboring fragments of a DNA molecule to the pore as well as to the plasmonic hot spot. Surface-enhanced Raman scattering from the exposed DNA fragments contains information about their nucleotide composition, possibly allowing the identification of the nucleotide sequence of a DNA molecule transported through the hot spot. The principles of plasmonic nanopore sequencing can be extended to detection of DNA modifications and RNA characterization.

  • 8.
    Blell, Rebecca
    et al.
    CNRS Institut Charles Sadron, France.
    Lin, Xiaofeng
    CNRS Institut Charles Sadron, France.
    Lindström, Tom
    RISE - Research Institutes of Sweden, Bioeconomy. RISE, Innventia.
    Ankerfors, Mikael
    RISE - Research Institutes of Sweden, Bioeconomy. RISE, Innventia.
    Pauly, Matthias
    CNRS Institut Charles Sadron, France; Université de Strasbourg, France.
    Felix, Olivier
    CNRS Institut Charles Sadron, France.
    Decher, Gero
    CNRS Institut Charles Sadron, France; Université de Strasbourg, France; International Center for Frontier Research in Chemistry, France.
    Generating in-Plane Orientational Order in Multilayer Films Prepared by Spray-Assisted Layer-by-Layer Assembly2017In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 11, no 1, p. 84-94Article in journal (Refereed)
    Abstract [en]

    We present a simple yet efficient method for orienting cellulose nanofibrils in layer-by-layer assembled films through spray-assisted alignment. While spraying at 90° against a receiving surface produces films with homogeneous in-plane orientation, spraying at smaller angles causes a macroscopic directional surface flow of liquid on the receiving surface and leads to films with substantial in-plane anisotropy when nanoscale objects with anisotropic shapes are used as components. First results with cellulose nanofibrils demonstrate that such fibrils are easily aligned by grazing incidence spraying to yield optically birefringent films over large surface areas. We show that the cellulosic nanofibrils are oriented parallel to the spraying direction and that the orientational order depends for example on the distance of the receiving surface from the spray nozzle. The alignment of the nanofibrils and the in-plane anisotropy of the films were independently confirmed by atomic force microscopy, optical microscopy between crossed polarizers, and the ellipsometric determination of the apparent refractive index of the film as a function of the in-plane rotation of the sample with respect to the plane of incidence of the ellipsometer.

  • 9.
    Börjesson, Anders
    et al.
    University of Borås, School of Engineering.
    Bolton, Kim
    University of Borås, School of Engineering.
    First Principles Studies of the Effect of Ostwald Ripening on Carbon Nanotube Chirality Distributions2011In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 5, no 2, p. 771-779Article in journal (Refereed)
    Abstract [en]

    The effect of Ostwald ripening of metal particles attached to carbon nanotubes has been studied using density functional theory. It has been confirmed that Ostwald ripening may be responsible for the termination of growth of carbon nanotube forests. It was seen that the Ostwald ripening of metal particles attached to carbon nanotubes is governed by a critical factor that depends on both the cluster size and the carbon nanotube chirality. For example, clusters attached to armchair and zigzag nanotubes of similar diameters will have different critical factors although the exact behavior may depend on which molecules are present in the surrounding medium. The critical factor was also observed to have a critical point with the effect that clusters with a narrow size distribution close to the critical point may experience a narrowing rather than a widening of the size distribution, as is the case for free clusters.

  • 10.
    Cai, Liangliang
    et al.
    Tongji Univ, Peoples R China.
    Yu, Xin
    Tongji Univ, Peoples R China.
    Liu, Mengxi
    Natl Ctr Nanosci and Technol, Peoples R China.
    Sun, Qiang
    Tongji Univ, Peoples R China.
    Bao, Meiling
    Tongji Univ, Peoples R China.
    Zha, Zeqi
    Natl Ctr Nanosci and Technol, Peoples R China; Univ Chinese Acad Sci, Peoples R China.
    Pan, Jinliang
    Natl Ctr Nanosci and Technol, Peoples R China; Univ Chinese Acad Sci, Peoples R China.
    Ma, Honghong
    Tongji Univ, Peoples R China.
    Ju, Huanxin
    Univ Sci and Technol China, Peoples R China.
    Hu, Shanwei
    Univ Sci and Technol China, Peoples R China.
    Xu, Liang
    Tongji Univ, Peoples R China.
    Zou, Jiacheng
    Tongji Univ, Peoples R China.
    Yuan, Chunxue
    Tongji Univ, Peoples R China.
    Jacob, Timo
    Ulm Univ, Germany.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Zhu, Junfa
    Univ Sci and Technol China, Peoples R China.
    Qu, Xiaohui
    Natl Ctr Nanosci and Technol, Peoples R China; Univ Chinese Acad Sci, Peoples R China.
    Xu, Wei
    Tongji Univ, Peoples R China.
    Direct Formation of C-C Double-Bonded Structural Motifs by On-Surface Dehalogenative Homocoupling of gem-Dibromomethyl Molecules2018In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 12, no 8, p. 7959-7966Article in journal (Refereed)
    Abstract [en]

    Conductive polymers are of great importance in a variety of chemistry-related disciplines and applications. The recently developed bottom-up on-surface synthesis strategy provides us with opportunities for the fabrication of various nanostructures in a flexible and facile manner, which could be investigated by high-resolution microscopic techniques in real space. Herein, we designed and synthesized molecular precursors functionalized with benzal gem-dibromomethyl groups. A combination of scanning tunneling microscopy, noncontact atomic force microscopy, high-resolution synchrotron radiation photoemission spectroscopy, and density functional theory calculations demonstrated that it is feasible to achieve the direct formation of C-C double-bonded structural motifs via on-surface dehalogenative homocoupling reactions on the Au(111) surface. Correspondingly, we convert the sp(3)-hybridized state to an sp(2)-hybridized state of carbon atoms, i.e., from an alkyl group to an alkenyl one. Moreover, by such a bottom-up strategy, we have successfully fabricated poly(phenylenevinylene) chains on the surface, which is anticipated to inspire further studies toward understanding the nature of conductive polymers at the atomic scale.

  • 11. Carville, N. Craig
    et al.
    Manzo, Michele
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Damm, Signe
    Castiella, Marion
    Collins, Liam
    Denning, Denise
    Weber, Stefan
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Rice, James
    Rodriguez, Brian
    Photoreduction of SERS-Active Metallic Nanostructures on Chemically Patterned Ferroelectric Crystals2012In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 6, no 8, p. 7373-7380Article in journal (Refereed)
    Abstract [en]

    Photodeposition of metallic nanostructures onto ferroelectric surfaces is typically based on patterning local surface reactivity via electric field poling. Here, we demonstrate metal deposition onto substrates which have been chemically patterned via proton exchange (i.e., without polarization reversal). The chemical patterning provides the ability to tailor the electrostatic fields near the surface of lithium niobate crystals, and these engineered fields are used to fabricate metallic nanostructures. The effect of the proton exchange process on the piezoelectric and electrostatic properties of the surface is characterized using voltage-modulated atomic force microscopy techniques, which, combined with modeling of the electric fields at the surface of the crystal, reveal that the deposition occurs preferentially along the boundary between ferroelectric and proton-exchanged regions. The metallic nanostructures have been further functionalized with a target probe molecule, 4-aminothiophenol, from which surface-enhanced Raman scattering (SERS) signal is detected, demonstrating the suitability of chemically patterned ferroelectrics as SERS-active templates.

  • 12.
    Charrier, Dimitri S. H.
    et al.
    Eindhoven University of Technology, Netherlands.
    Kemerink, Martijn
    Eindhoven University of Technology, Netherlands.
    Smalbrugge, Barry E.
    Eindhoven University of Technology, Netherlands.
    de Vries, Tjibbe
    Eindhoven University of Technology, Netherlands.
    Janssen, Rene A. J.
    Eindhoven University of Technology, Netherlands.
    Real versus measured surface potentials in scanning Kelvin probe microscopy2008In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 2, no 4, p. 622-626Article in journal (Refereed)
    Abstract [en]

    Noncontact potentiometry or scanning Kelvin probe microscopy (SKPM) is a widely used technique to study charge injection and transport in (in)organic devices by measuring a laterally resolved local potential. This technique suffers from the significant drawback that experimentally obtained curves do not generally reflect the true potential profile in the device due to nonlocal coupling between the probing tip and the device. In this work, we quantitatively explain the experimental SKPM response and by doing so directly link theoretical device models to real observables. In particular, the model quantitatively explains the effects of the tip-sample distance and the dependence on the orientation of the probing tip with respect to the device.

  • 13.
    Chen, Guanying
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ohulchanskyy, T. Y.
    Liu, S.
    Law, W. -C
    Wu, F.
    Swihart, M. T.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Prasad, P. N.
    Core/shell NaGdF 4:Nd 3+/NaGdF 4 nanocrystals with efficient near-infrared to near-infrared downconversion photoluminescence for bioimaging applications2012In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 6, no 4, p. 2969-2977Article in journal (Refereed)
    Abstract [en]

    We have synthesized core/shell NaGdF 4:Nd 3+/NaGdF 4 nanocrystals with an average size of 15 nm and exceptionally high photoluminescence (PL) quantum yield. When excited at 740 nm, the nanocrystals manifest spectrally distinguished, near-infrared to near-infrared (NIR-to-NIR) downconversion PL peaked at ∌900, ∌1050, and ∌1300 nm. The absolute quantum yield of NIR-to-NIR PL reached 40% for core-shell nanoparticles dispersed in hexane. Time-resolved PL measurements revealed that this high quantum yield was achieved through suppression of nonradiative recombination originating from surface states and cross relaxations between dopants. NaGdF 4:Nd 3+/NaGdF 4 nanocrystals, synthesized in organic media, were further converted to be water-dispersible by eliminating the capping ligand of oleic acid. NIR-to-NIR PL bioimaging was demonstrated both in vitro and in vivo through visualization of the NIR-to-NIR PL at ∌900 nm under incoherent lamp light excitation. The fact that both excitation and the PL of these nanocrystals are in the biological window of optical transparency, combined with their high quantum efficiency, spectral sharpness, and photostability, makes these nanocrystals extremely promising as optical biomaging probes.

  • 14.
    Chen, Guanying
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Shen, Jie
    Ohulchanskyy, Tymish Y.
    Patel, Nayan J.
    Kutikov, Artem
    Li, Zhipeng
    Song, Jie
    Pandey, Ravindra K.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Prasad, Paras N.
    Han, Gang
    (alpha-NaYbF4:Tm3+)/CaF2 Core/Shell Nanoparticles with Efficient Near-Infrared to Near-Infrared Upconversion for High-Contrast Deep Tissue Bioimaging2012In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 6, no 9, p. 8280-8287Article in journal (Refereed)
    Abstract [en]

    We describe the development of novel and biocompatible core/shell (alpha-NaYbF4:Tm3+)/CaF2 nanoparticles that exhibit highly efficient NIRin-NIROut upconversion (UC) for high contrast and deep bioimaging. When excited at similar to 980 nm, these nanoparticles emit photoluminescence (PL) peaked at similar to 800 nm. The quantum yield of this UC PL under low power density excitation (similar to 0.3 W/cm(2)) is 0.6 +/- 0.1%. This high UC PL efficiency is realized by suppressing surface quenching effects via heteroepitaxial growth of a biocompatible CaF2 shell, which results in a 35-fold increase in the intensity of UC PL from the core. Small-animal whole-body UC PL imaging with exceptional contrast (signal-to-background ratio of 310) is shown using BALB/c mice intravenously injected with aqueously dispersed nanoparticles (700 pmol/kg). High-contrast UC PL imaging of deep tissues is also demonstrated, using a nanoparticle-loaded synthetic fibrous mesh wrapped around rat femoral bone and a cuvette with nanoparticle aqueous dispersion covered with a 3.2 cm thick animal tissue (pork).

  • 15. Chen, Si
    et al.
    Svedendahl, Mikael
    Antosiewicz, Tomasz J
    Käll, Mikael
    Plasmon-enhanced enzyme-linked immunosorbent assay on large arrays of individual particles made by electron beam lithography.2013In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 7, no 10Article in journal (Refereed)
    Abstract [en]

    Ultrasensitive biosensing is one of the main driving forces behind the dynamic research field of plasmonics. We have previously demonstrated that the sensitivity of single nanoparticle plasmon spectroscopy can be greatly enhanced by enzymatic amplification of the refractive index footprint of individual protein molecules, so-called plasmon-enhanced enzyme-linked immunosorbent assay (ELISA). The technique, which is based on generation of an optically dense precipitate catalyzed by horseradish peroxidase at the metal surface, allowed for colorimetric analysis of ultralow molecular surface coverages with a limit of detection approaching the single molecule limit. However, the plasmonic response induced by a single enzyme can be expected to vary for a number of reasons, including inhomogeneous broadening of the sensing properties of individual particles, variation in electric field enhancement over the surface of a single particle and variation in size and morphology of the enzymatic precipitate. In this report, we discuss how such inhomogeneities affect the possibility to quantify the number of molecules bound to a single nanoparticle. The discussion is based on simulations and measurements of large arrays of well-separated gold nanoparticles fabricated by electron beam lithography (EBL). The new data confirms the intrinsic single-molecule sensitivity of the technique but we were not able to clearly resolve the exact number of adsorbed molecules per single particle. The results indicate that the main sources of uncertainty come from variations in sensitivity across the surface of individual particles and between different particles. There is also a considerable uncertainty in the actual precipitate morphology produced by individual enzyme molecules. Possible routes toward further improvements of the methodology are discussed.

  • 16.
    Chen, Xi
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Chen, Yiting
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Yan, Min
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Qiu, Min
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Nanosecond Photothermal Effects in Plasmonic Nanostructures2012In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 6, no 3, p. 2550-2557Article in journal (Refereed)
    Abstract [en]

    Photothermal effects in plasmonic nanostructures have great potentials in applications for photothermal cancer therapy, optical storage, thermo-photovoltaics, etc. However, the transient temperature behavior of a nanoscale material system during an ultrafast photothermal process has rarely been accurately investigated. Here a heat transfer model is constructed to investigate the temporal and spatial variation of temperature in plasmonic gold nanostructures. First, as a benchmark scenario, we study the light-induced heating of a gold nanosphere in water and calculate the relaxation time of the nanosphere excited by a modulated light. Second, we investigate heating and reshaping of gold nanoparticles in a more complex metamaterial absorber structure induced by a nanosecond pulsed light. The model shows that the temperature of the gold nanoparticles can be raised from room temperature to >795 K in just a few nanoseconds with a low light luminance, owing to enhanced light absorption through strong plasmonic resonance. Such quantitative predication of temperature change, which Is otherwise formidable to measure experimentally, can serve as an excellent guideline for designing devices for ultrafast photothermal applications.

  • 17. Chernov, Alexander I
    et al.
    Fedotov, Pavel V
    Talyzin, Alexandr
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Suarez Lopez, Inma
    Anoshkin, Ilya V
    Nasibulin, Albert G
    Kauppinen, Esko I
    Obraztsova, Elena D
    Optical properties of graphene nanoribbons encapsulated in single-walled carbon nanotubes2013In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 7, no 7, p. 6346-6353Article in journal (Refereed)
    Abstract [en]

    We report the photoluminescence (PL) from graphene nanoribbons (GNRs) encapsulated in single-walled carbon nanotubes (SWCNTs). New PL spectral features originating from GNRs have been detected in the visible spectral range. PL peaks from GNRs have resonant character, and their positions depend on the ribbon geometrical structure in accordance with the theoretical predictions. GNRs were synthesized using confined polymerization and fusion of coronene molecules. GNR@SWCNTs material demonstrates a bright photoluminescence both in infrared (IR) and visible regions. The photoluminescence excitation mapping in the near-IR spectral range has revealed the geometry-dependent shifts of the SWCNT peaks (up to 11 meV in excitation and emission) after the process of polymerization of coronene molecules inside the nanotubes. This behavior has been attributed to the strain of SWCNTs induced by insertion of the coronene molecules.

  • 18. Chilkoor, Govinda
    et al.
    Karanam, Sushma Priyanka
    Star, Shane
    Shrestha, Namita
    Sani, Rajesh K.
    Upadhyayula, Venkata K. K.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ghoshal, Debjit
    Koratkar, Nikhil A.
    Meyyappan, M.
    Gadhamshetty, Venkataramana
    Hexagonal Boron Nitride: The Thinnest Insulating Barrier to Microbial Corrosion2018In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 12, no 3, p. 2242-2252Article in journal (Refereed)
    Abstract [en]

    We report the use of a single layer of two-dimensional hexagonal boron nitride (SL-hBN) as the thinnest insulating barrier to microbial corrosion induced by the sulfate-reducing bacteria Desulfovibrio alaskensis G20. We used electrochemical methods to assess the corrosion resistance of SL-hBN on copper against the effects of both the planktonic and sessile forms of the sulfate-reducing bacteria. Cyclic voltammetry results show that SL-hBN-Cu is effective in suppressing corrosion effects of the planktonic cells at potentials as high as 0.2 V (vs Ag/AgCl). The peak anodic current for the SL-hBN coatings is ∼36 times lower than that of bare Cu. Linear polarization resistance tests confirm that the SL-hBN coatings serve as a barrier against corrosive effects of the G20 biofilm when compared to bare Cu. The SL-hBN serves as an impermeable barrier to aggressive metabolites and offers ∼91% corrosion inhibition efficiency, which is comparable to much thicker commercial coatings such as polyaniline. In addition to impermeability, the insulating nature of SL-hBN suppresses galvanic effects and improves its ability to combat microbial corrosion.

  • 19. Copolovici, Dana Maria
    et al.
    Langel, Kent
    Eriste, Elo
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry. University of Tartu, Estonia.
    Cell-Penetrating Peptides: Design, Synthesis, and Applications2014In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 8, no 3, p. 1972-1994Article, review/survey (Refereed)
    Abstract [en]

    The intrinsic property of cell-penetrating peptides (CPPs) to deliver therapeutic molecules (nucleic acids, drugs, imaging agents) to cells and tissues in a nontoxic manner has indicated that they may be potential components of future drugs and disease diagnostic agents. These versatile peptides are simple to synthesize, functionalize, and characterize yet are able to deliver covalently or noncovalently conjugated bioactive cargos (from small chemical drugs to large plasmid DNA) inside cells, primarily via endocytosis, in order to obtain high levels of gene expression, gene silencing, or tumor targeting. Typically, CPPs are often passive and nonselective yet must be functionalized or chemically modified to create effective delivery vectors that succeed in targeting specific cells or tissues. Furthermore, the design of clinically effective systemic delivery systems requires the same amount of attention to detail in both design of the delivered cargo and the cell-penetrating peptide used to deliver it.

  • 20.
    Dahlin, Andreas B.
    et al.
    Division of Solid State Physics, Department of Physics, Lund University, Lund, Sweden..
    Jonsson, Peter
    Division of Solid State Physics, Department of Physics, Lund University, Lund, Sweden..
    Jonsson, Magnus P.
    Division of Solid State Physics, Department of Physics, Lund University, Lund, Sweden..
    Schmid, Emanuel
    Division of Solid State Physics, Department of Physics, Lund University, Lund, Sweden..
    Zhou, Ye
    Division of Solid State Physics, Department of Physics, Lund University, Lund, Sweden..
    Hook, Fredrik
    Division of Solid State Physics, Department of Physics, Lund University, Lund, Sweden..
    Synchronized Quartz Crystal Microbalance and Nanoplasmonic Sensing of Biomolecular Recognition Reactions2008In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 2, no 10, p. 2174-2182Article in journal (Refereed)
    Abstract [en]

    We present a method providing synchronized measurements using the two techniques: quartz crystal microbalance with dissipation (QCM-D) monitoring and localized surface plasmon resonance (LSPR). This was achieved by letting a thin gold film perforated with short-ranged ordered plasmon-active nanoholes act as one of the electrodes of a QCM-D crystal. This enabled transmission-mode optical spectroscopy to be used to temporally resolve colorimetric changes of the LSPR active substrate induced upon bionnolecular binding events. The LSPR response could thus be compared with simultaneously obtained changes in resonance frequency, Delta f, and energy dissipation, AD, of the QCM-D device. Since the LSPR technique is preferentially sensitive to changes within the voids of the nanoholes, while the QCM-D technique is preferentially sensitive to reactions on the planar region between the holes, a surface chemistry providing the same binding kinetics on both gold and silica was used. This was achieved by coating the substrate with poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG), which was shown to bind in the same manner on silica and gold modified with a carboxyl-terminated thiol. In this way, the combined setup provided new information about structural changes upon PLL-g-PEG adsorption. We also demonstrate subsequent binding of NeutrAvidin and an immunoreaction utilizing biotin-modified IgG. The combined information from the synchronized measurements was also used in a new way to estimate the sensing volume of the LSPR sensor.

  • 21.
    Dahlqvist, Martin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Petruhins, Andrejs
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Origin of Chemically Ordered Atomic Laminates (i-MAX): Expanding the Elemental Space by a Theoretical/Experimental Approach2018In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 12, no 8, p. 7761-7770Article in journal (Refereed)
    Abstract [en]

    With increased chemical diversity and structural complexity comes the opportunities for innovative materials possessing advantageous properties. Herein, we combine predictive first-principles calculations with experimental synthesis, to explore the origin of formation of the atomically laminated i-MAX phases. By probing (Mo2/3M1/32)(2)AC (where M-2 = Sc, Y and A = Al, Ga, In, Si, Ge, In), we predict seven stable i-MAX phases, five of which should have a retained stability at high temperatures. (Mo2/3Sc1/3)(2)GaC and (Mo2/3Y1/3)(2)GaC were experimentally verified, displaying the characteristic in-plane chemical order of Mo and Sc/Y and Kagome-like ordering of the A-element. We suggest that the formation of i-MAX phases requires a significantly different size of the two metals, and a preferable smaller size of the A-element. Furthermore, the population of antibonding orbitals should be minimized, which for the metals herein (Mo and Sc/Y) means that A elements from Group 13 (Al, Ga, In) are favored over Group 14 (Si, Ge, Sn). Using these guidelines, we foresee a widening of elemental space for the family of i-MAX phases and expect more phases to be synthesized, which will realize useful properties. Furthermore, based on i-MAX phases as parent materials for 2D MXenes, we also expect that the range of MXene compositions will be expanded.

  • 22.
    Dankert, Andre
    et al.
    Chalmers, Dept Microtechnol & Nanosci, SE-41296 Gothenburg, Sweden..
    Pashaei, Parham
    Chalmers, Dept Microtechnol & Nanosci, SE-41296 Gothenburg, Sweden..
    Kamalakar, M. Venkata
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics. Chalmers, Dept Microtechnol & Nanosci, SE-41296 Gothenburg, Sweden.
    Gaur, Anand P. S.
    Univ Puerto Rico, Dept Phys, San Juan, PR 00931 USA.;Univ Puerto Rico, Inst Funct Nanomat, San Juan, PR 00931 USA.;Iowa State Univ, Mech Engn Dept, Ames, IA 50011 USA..
    Sahoo, Satyaprakash
    Univ Puerto Rico, Dept Phys, San Juan, PR 00931 USA.;Univ Puerto Rico, Inst Funct Nanomat, San Juan, PR 00931 USA.;Inst Phys, Bhubaneswar 751005, Odisha, India..
    Rungger, Ivan
    Natl Phys Lab, Teddington TW11 0LW, Middx, England..
    Narayan, Awadhesh
    Trinity Coll Dublin, AMBER & CRANN Inst, Sch Phys, Dublin 2, Ireland.;Swiss Fed Inst Technol, Mat Theory, Wolfgang Pauli Str 27, CH-8093 Zurich, Switzerland..
    Dolui, Kapildeb
    Trinity Coll Dublin, AMBER & CRANN Inst, Sch Phys, Dublin 2, Ireland.;Univ Delaware, Dept Phys & Astron, Newark, DE 19716 USA..
    Hoque, Md. Anamul
    Chalmers, Dept Microtechnol & Nanosci, SE-41296 Gothenburg, Sweden..
    Patel, Ram Shanker
    Birla Inst Technol & Sci, Dept Phys, Pilani KK Birla Goa Campus, Zuarinagar 403726, Goa, India..
    de Jong, Michel P.
    Univ Twente, MESA Inst Nanotechnol, NL-7500 AE Enschede, Netherlands..
    Katiyar, Ram S.
    Univ Puerto Rico, Dept Phys, San Juan, PR 00931 USA.;Univ Puerto Rico, Inst Funct Nanomat, San Juan, PR 00931 USA..
    Sanvito, Stefano
    Trinity Coll Dublin, AMBER & CRANN Inst, Sch Phys, Dublin 2, Ireland..
    Dash, Saroj P.
    Chalmers, Dept Microtechnol & Nanosci, SE-41296 Gothenburg, Sweden..
    Spin-Polarized Tunneling through Chemical Vapor Deposited Multilayer Molybdenum Disulfide2017In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 11, no 6, p. 6389-6395Article in journal (Refereed)
    Abstract [en]

    The two-dimensional (2D) semiconductor molybdenum disulfide (MoS2) has attracted widespread attention for its extraordinary electrical-, optical-, spin-, and valley-related properties. Here, we report on spin-polarized tunneling through chemical vapor deposited multilayer MoS2 (similar to 7 nm) at room temperature in a vertically fabricated spin-valve device. A tunnel magnetoresistance (TMR) of 0.5-2% has been observed, corresponding to spin polarization of 5-10% in the measured temperature range of 300-75 K. First-principles calculations for ideal junctions result in a TMR up to 8% and a spin polarization of 26%. The detailed measurements at different temperature, bias voltages, and density functional theory calculations provide information about spin transport mechanisms in vertical multilayer MoS2 spin-valve devices. These findings form a platform for exploring spin functionalities in 2D semiconductors and understanding the basic phenomena that control their performance.

  • 23.
    Daukiya, Lakshya
    et al.
    Univ Haute Alsace, Inst Sci Mat Mulhouse, CNRS, UMR 7361, 3Bis,Rue Alfred Werner, F-68093 Mulhouse, France..
    Mattioli, Cristina
    CNRS, UPR 8011, CEMES, Nanosci Grp, 29 Rue Jeanne Marvig,BP 94347, F-31055 Toulouse, France..
    Aubel, Dominique
    Univ Haute Alsace, Inst Sci Mat Mulhouse, CNRS, UMR 7361, 3Bis,Rue Alfred Werner, F-68093 Mulhouse, France..
    Hajjar-Garreau, Samar
    Univ Haute Alsace, Inst Sci Mat Mulhouse, CNRS, UMR 7361, 3Bis,Rue Alfred Werner, F-68093 Mulhouse, France..
    Vonau, Francois
    Univ Haute Alsace, Inst Sci Mat Mulhouse, CNRS, UMR 7361, 3Bis,Rue Alfred Werner, F-68093 Mulhouse, France..
    Denys, Emmanuel
    Univ Haute Alsace, Inst Sci Mat Mulhouse, CNRS, UMR 7361, 3Bis,Rue Alfred Werner, F-68093 Mulhouse, France..
    Reiter, Guenter
    Univ Freiburg, Inst Phys, Hermann Herder Str 3, D-79104 Freiburg, Germany..
    Fransson, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Perrin, Elsa
    UPMC Univ Paris 06, CNRS, Dept Chim, Ecole Normale Super,PSL Res Univ, 24 Rue Lhomond, F-75005 Paris, France..
    Bocquet, Marie-Laure
    UPMC Univ Paris 06, CNRS, Dept Chim, Ecole Normale Super,PSL Res Univ, 24 Rue Lhomond, F-75005 Paris, France..
    Bena, Cristina
    CEA Saclay, Inst Phys Theor, Orme Merisiers, F-91190 Gif Sur Yvette, France.;Paris Sud, UMR 8502, CNRS, Lab Phys Solides, F-91405 Orsay, France..
    Gourdon, Andre
    CNRS, UPR 8011, CEMES, Nanosci Grp, 29 Rue Jeanne Marvig,BP 94347, F-31055 Toulouse, France..
    Simon, Laurent
    Univ Haute Alsace, Inst Sci Mat Mulhouse, CNRS, UMR 7361, 3Bis,Rue Alfred Werner, F-68093 Mulhouse, France..
    Covalent Functionalization by Cycloaddition Reactions of Pristine Defect-Free Graphene2017In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 11, no 1, p. 627-634Article in journal (Refereed)
    Abstract [en]

    Based on a low-temperature scanning tunneling microscopy study, we present a direct visualization of a cycloaddition reaction performed for some specific fluorinated maleimide molecules deposited on graphene. Up to now, it was widely admitted that such a cycloaddition reaction can not happen without pre-existing defects. However, our study shows that the cycloaddition reaction can be carried out on a defect-free basal graphene plane at room temperature. In the course of covalently grafting the molecules to graphene, the sp(2) conjugation of carbon atoms was broken, and local sp(3) bonds were created. The grafted molecules perturbed the graphene lattice, generating a standing-wave pattern with an anisotropy which was attributed to a (1,2) cycloaddition, as revealed by T-matrix approximation calculations. DFT calculations showed that while both (1,4) and (1,2) cycloadditions were possible on free-standing graphene, only the (1,2) cycloaddition could be obtained for graphene on SiC(0001). Globally averaging spectroscopic techniques, XPS and ARPES, were used to determine the modification in the elemental composition of the samples induced by the reaction, indicating an opening of an electronic gap in graphene.

  • 24. Ding, Fei
    et al.
    Wang, Zhuoxian
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. Zhejiang University, China.
    Shalaev, Vladimir M.
    Kildishev, Alexander V.
    Broadband High-Efficiency Half-Wave Plate: A Supercell-Based Plasmonic Metasurface Approach2015In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 9, no 4, p. 4111-4119Article in journal (Refereed)
    Abstract [en]

    We design, fabricate, and experimentally demonstrate an ultrathin, broadband half-wave plate in the near-infrared range using a plasmonic metasurface. The simulated results show that the linear polarization conversion efficiency is over 97% with over 90% reflectance across an 800 nm bandwidth. Moreover, simulated and experimental results indicate that such broadband and high-efficiency performance is also sustained over a wide range of incident angles. To further obtain a background-free half-wave plate, we arrange such a plate as a periodic array of integrated supercells made of several plasmonic antennas with high linear polarization conversion efficiency, consequently achieving a reflection-phase gradient for the cross-polarized beam. In this design, the anomalous (cross-polarized) and the normal (copolarized) reflected beams become spatially separated, hence enabling highly efficient and robust, background-free polarization conversion along with broadband operation. Our results provide strategies for creating compact, integrated, and high-performance plasmonic circuits and devices.

  • 25. Dreiser, Jan
    et al.
    Waeckerlin, Christian
    Ali, Md Ehesan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Piamonteze, Cinthia
    Donati, Fabio
    Singha, Aparajita
    Pedersen, Kasper Steen
    Rusponi, Stefano
    Bendix, Jesper
    Oppeneer, Peter M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Jung, Thomas A.
    Brune, Harald
    Exchange Interaction of Strongly Anisotropic Tripodal Erbium Single-Ion Magnets with Metallic Surfaces2014In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 8, no 5, p. 4662-4671Article in journal (Refereed)
    Abstract [en]

    We present a comprehensive study of Er(trensal) single-ion magnets deposited in ultrahigh vacuum onto metallic surfaces. X-ray photoelectron spectroscopy reveals that the molecular structure is preserved after sublimation, and that the molecules are physisorbed on Au(111) while they are chemisorbed on a Ni thin film on 0(100) single-crystalline surfaces. X-ray magnetic circular dichroism (XMCD) measurements performed on Au(111) samples covered with molecular monolayers held at temperatures down to 4 K suggest that the easy axes of the strongly anisotropic molecules are randomly oriented. Furthermore XMCD indicates a weak antiferromagnetic exchange coupling between the single-ion magnets and the ferromagnetic Ni/Cu(100) substrate. For the latter case, spin-Hamiltonian fits to the XMCD M(H) suggest a significant structural distortion of the molecules. Scanning tunneling microscopy reveals that the molecules are mobile on Au(111) at room temperature, whereas they are more strongly attached on Ni/Cu(100). X-ray photoelectron spectroscopy results provide evidence for the chemical bonding between Er(trensal) molecules and the Ni substrate. Density functional theory calculations support these findings and, in addition, reveal the most stable adsorption configuration on Ni/Cu(100) as well as the Ni-Er exchange path. Our study suggests that the magnetic moment of Er(trensal) can be stabilized via suppression of quantum tunneling of magnetization by exchange coupling to the Ni surface atoms. Moreover, it opens up pathways toward optical addressing of surface-deposited single-ion magnets.

  • 26.
    Eriksson, Mimmi
    et al.
    RISE Res Inst Sweden, Biosci & Mat Surface, Proc & Formulat, SE-11486 Stockholm, Sweden.
    Tuominen, Mikko
    RISE Res Inst Sweden, Biosci & Mat Surface, Proc & Formulat, SE-11486 Stockholm, Sweden..
    Jarn, Mikael
    RISE Res Inst Sweden, Biosci & Mat Surface, Proc & Formulat, SE-11486 Stockholm, Sweden..
    Claesson, Per M.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. RISE Research Institutes of Sweden, Bioscience and Materials − Surface, Process and Formulation, SE-114 86 Stockholm, Sweden.
    Wallqvist, Viveca
    RISE Res Inst Sweden, Biosci & Mat Surface, Proc & Formulat, SE-11486 Stockholm, Sweden..
    Butt, Hans Juergen
    Max Planck Inst Polymer Res, Dept Phys Interfaces, Ackermannweg 10, DE-55128 Mainz, Germany..
    Vollmer, Doris
    Max Planck Inst Polymer Res, Dept Phys Interfaces, Ackermannweg 10, DE-55128 Mainz, Germany..
    Kappl, Michael
    Max Planck Inst Polymer Res, Dept Phys Interfaces, Ackermannweg 10, DE-55128 Mainz, Germany..
    Schoelkopf, Joachim
    Omya Int AG, Baslerstr 42, CH-4665 Oftringen, Switzerland..
    Gane, Patrick A. C.
    Omya Int AG, Baslerstr 42, CH-4665 Oftringen, Switzerland.;Aalto Univ, Sch Chem Engn, Dept Bioprod & Biosyst, FI-00076 Aalto, Finland..
    Teisala, Hannu
    Max Planck Inst Polymer Res, Dept Phys Interfaces, Ackermannweg 10, DE-55128 Mainz, Germany..
    Swerin, Agne
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. RISE Res Inst Sweden, Biosci & Mat Surface, Proc & Formulat, SE-11486 Stockholm, Sweden..
    Direct Observation of Gas Meniscus Formation on a Superhydrophobic Surface2019In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 13, no 2, p. 2246-2252Article in journal (Refereed)
    Abstract [en]

    The formation of a bridging gas meniscus via cavitation or nanobubbles is considered the most likely origin of the submicrometer long-range attractive forces measured between hydrophobic surfaces in aqueous solution. However, the dynamics of the formation and evolution of the gas meniscus is still under debate, in particular, in the presence of a thin air layer on a superhydrophobic surface. On superhydrophobic surfaces the range can even exceed 10 mu m. Here, we report microscopic images of the formation and growth of a gas meniscus during force measurements between a superhydrophobic surface and a hydrophobic microsphere immersed in water. This is achieved by combining laser scanning confocal microscopy and colloidal probe atomic force microscopy. The configuration allows determination of the volume and shape of the meniscus, together with direct calculation of the Young-Laplace capillary pressure. The long-range attractive interactions acting on separation are due to meniscus formation and volume growth as air is transported from the surface layer.

  • 27.
    Eriksson, Mimmi
    et al.
    RISE - Research Institutes of Sweden, Bioscience and Materials, Surface, Process and Formulation.
    Tuominen, Mikko
    RISE - Research Institutes of Sweden, Bioscience and Materials, Surface, Process and Formulation.
    Järn, Mikael
    RISE - Research Institutes of Sweden, Bioscience and Materials, Surface, Process and Formulation.
    Claesson, Per Martin
    RISE - Research Institutes of Sweden, Bioscience and Materials, Surface, Process and Formulation. KTH Royal Institute of Technology, Sweden.
    Wallqvist, Viveca
    RISE - Research Institutes of Sweden, Bioscience and Materials, Surface, Process and Formulation.
    Butt, Hans-Jürgen
    Max Planck Institute for Polymer Research, Germany.
    Vollmer, Doris
    Max Planck Institute for Polymer Research, Germany.
    Kappl, Michael
    Max Planck Institute for Polymer Research, Germany.
    Schoelkopf, Joachim
    Omya International AG, Switzerland.
    Gane, Patrick A C
    Omya International AG, Switzerland.
    Teisala, Hannu
    Aalto University, Finland.
    Swerin, Agne
    RISE - Research Institutes of Sweden, Bioscience and Materials, Surface, Process and Formulation.
    Direct Observation of Gas Meniscus Formation on a Superhydrophobic Surface2019In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 13, no 2, p. 2246-2252Article in journal (Refereed)
    Abstract [en]

    The formation of a bridging gas meniscus via cavitation or nanobubbles is considered the most likely origin of the submicrometer long-range attractive forces measured between hydrophobic surfaces in aqueous solution. However, the dynamics of the formation and evolution of the gas meniscus is still under debate, in particular, in the presence of a thin air layer on a superhydrophobic surface. On superhydrophobic surfaces the range can even exceed 10 μm. Here, we report microscopic images of the formation and growth of a gas meniscus during force measurements between a superhydrophobic surface and a hydrophobic microsphere immersed in water. This is achieved by combining laser scanning confocal microscopy and colloidal probe atomic force microscopy. The configuration allows determination of the volume and shape of the meniscus, together with direct calculation of the Young-Laplace capillary pressure. The long-range attractive interactions acting on separation are due to meniscus formation and volume growth as air is transported from the surface layer.

  • 28. Fan, Ke
    et al.
    Zou, Haiyuan
    Lu, Yue
    Beijing Univ Technol, Inst Microstruct & Properties Adv Mat, Beijing 100124, Peoples R China..
    Chen, Hong
    Li, Fusheng
    Liu, Jinxuan
    Sun, Licheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Tong, Lianpeng
    Toney, Michael F.
    Sui, Manling
    Yu, Jiaguo
    Direct Observation of Structural Evolution of Metal Chalcogenide in Electrocatalytic Water Oxidation2018In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 12, no 12, p. 12369-12379Article in journal (Refereed)
    Abstract [en]

    As one of the most remarkable oxygen evolution reaction (OER) electrocatalysts, metal chalcogenides have been intensively reported during the past few decades because of their high OER activities. It has been reported that electron-chemical conversion of metal OER chalcogenides into oxides/hydroxides would take place after the OER. However, the transition mechanism of such unstable structures, as well as the real active sites and catalytic activity during the OER for these electrocatalysts, has not been understood yet; therefore a direct observation for the electrocatalytic water oxidation process, especially at nano or even angstrom scale, is urgently needed. In this research, by employing advanced Cs-corrected transmission electron microscopy (TEM), a step by step oxidational evolution of amorphous electrocatalyst CoSx into crystallized CoOOH in the OER has been in situ captured: irreversible conversion of CoSx to crystallized CoOOH is initiated on the surface of the electrocatalysts with a morphology change via Co(OH)(2) intermediate during the OER measurement, where CoOOH is confirmed as the real active species. Besides, this transition process has also been confirmed by multiple applications of X-ray photoelectron spectroscopy (XPS), in situ Fourier-transform infrared spectroscopy (FTIR), and other ex situ technologies. Moreover, on the basis of this discovery, a high-efficiency electrocatalyst of a nitrogen-doped graphene foam (NGF) coated by CoSx has been explored through a thorough structure transformation of CoOOH. We believe this in situ and in-depth observation of structural evolution in the OER measurement can provide insights into the fundamental understanding of the mechanism for the OER catalysts, thus enabling the more rational design of low-cost and high-efficient electrocatalysts for water splitting.

  • 29.
    Feuz, Laurent
    et al.
    Department of Applied Physics, Chalmers University of Technology, SE-41296 Gothenburg, Sweden.
    Jonsson, Peter
    Department of Applied Physics, Chalmers University of Technology, SE-41296 Gothenburg, Sweden.
    Jonsson, Magnus P.
    Department of Applied Physics, Chalmers University of Technology, SE-41296 Gothenburg, Sweden.
    Hook, Fredrik
    Department of Applied Physics, Chalmers University of Technology, SE-41296 Gothenburg, Sweden.
    Improving the Limit of Detection of Nanoscale Sensors by Directed Binding to High-Sensitivity Areas2010In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 4, no 4, p. 2167-2177Article in journal (Refereed)
    Abstract [en]

    The revelation of protein protein-interactions is one of the main preoccupations in the field of proteomics. Nanoplasmonics has emerged as an attractive surface-based technique because of its ability to sense protein binding under physiological conditions in a label-free manner. Here, we use short-range ordered holes with a diameter of similar to 150 nm and a depth of similar to 50 nm as a nanoplasmonic template. A similar to 40 nm high cylindrical region of Au is exposed on the walls of the holes only, while the rest of the surface consists of TiO(2). Since the sensitivity is confined to the nanometric holes, the use of two different materials for the sensor substrate offers the opportunity to selectively bind proteins to the most sensitive Au regions on the sensor surface. This was realized by applying material-selective poly(ethylene glycol)-based surface chemistry, restricting NeutrAvidin binding to surface-immobilized biotin on the Au areas only. We show that under mass-transport limited conditions (low nM bulk concentrations), the initial time-resolved response of uptake could be increased by a factor of almost 20 compared with the case where proteins were allowed to bind on the entire sensor surface and stress the generic relevance of this concept for nanoscale sensors. In the scope of further optimizing the limit of detection (LOD) of the sensor structure, we present finite-element (FE) simulations to unravel spatially resolved binding rates. These revealed that the binding rates in the holes occur in a highly inhomogeneous manner with highest binding rates observed at the upper rim of the holes and the lowest rates observed at the bottom of the holes. By assuming a plasmonic field distribution with enhanced sensitivity at the Au-TiO(2)interface, the FE simulations reproduced the experimental findings qualitatively.

  • 30.
    Filippov, Stanislav
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Puttisong, Yuttapoom
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Huang, Yuqing
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Buyanova, Irina A
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Suraprapapich, Suwaree
    Department of Electrical and Computer Engineering, University of California, La Jolla, California, United States.
    Tu, Charles. W.
    Department of Electrical and Computer Engineering, University of California, La Jolla, California 92093, United States.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Exciton Fine-Structure Splitting in Self-Assembled Lateral InAs/GaAs Quantum-Dot Molecular Structures2015In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 9, no 6, p. 5741-5749Article in journal (Refereed)
    Abstract [en]

    Fine-structure splitting (FSS) of excitons in semiconductor nanostructures is a key parameter that has significant implications in photon entanglement and polarization conversion between electron spins and photons, relevant to quantum information technology and spintronics. Here, we investigate exciton FSS in self-organized lateral InAs/GaAs quantum-dot molecular structures (QMSs) including laterally aligned double quantum dots (DQDs), quantum-dot clusters (QCs), and quantum rings (QRs), by employing polarization-resolved microphotoluminescence (μPL) spectroscopy. We find a clear trend in FSS between the studied QMSs depending on their geometric arrangements, from a large FSS in the DQDs to a smaller FSS in the QCs and QRs. This trend is accompanied by a corresponding difference in the optical polarization directions of the excitons between these QMSs, namely, the bright-exciton lines are linearly polarized preferably along or perpendicular to the [11̅0] crystallographic axis in the DQDs that also defines the alignment direction of the two constituting QDs, whereas in the QCs and QRs, the polarization directions are randomly oriented. We attribute the observed trend in the FSS to a significant reduction of the asymmetry in the lateral confinement potential of the excitons in the QRs and QCs as compared with the DQDs, as a result of a compensation between the effects of lateral shape anisotropy and piezoelectric field. Our work demonstrates that FSS strongly depends on the geometric arrangements of the QMSs, which effectively tune the degree of the compensation effects and are capable of reducing FSS even in a strained QD system to a limit similar to strain-free QDs. This approach provides a pathway in obtaining high-symmetry quantum emitters desirable for realizing photon entanglement and spintronic devices based on such nanostructures, utilizing an uninterrupted epitaxial growth procedure without special requirements for lattice-matched materials combinations, specific substrate orientations, and nanolithography.

  • 31.
    Foroughi, Javad
    et al.
    Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, University of Wollongong, Wollongong, NSW, Australia; Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, Australia.
    Spinks, Geoffrey M
    Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, University of Wollongong, Wollongong, NSW, Australia.
    Aziz, Shazed
    Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, University of Wollongong, Wollongong, NSW, Australia.
    Mirabedini, Azadeh
    Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, University of Wollongong, Wollongong, NSW, Australia.
    Jeiranikhameneh, Ali
    Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, University of Wollongong, Wollongong, NSW, Australia.
    Wallace, Gordon G
    Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, University of Wollongong, Wollongong, NSW, Australia.
    Kozlov, Mikhail E
    Alan G MacDiarmid NanoTech Institute, University of Texas at Dallas, Richardson, Texas, United States.
    Baughman, Ray H
    Alan G MacDiarmid NanoTech Institute, University of Texas at Dallas, Richardson, Texas, United States.
    Knitted Carbon-Nanotube-Sheath/Spandex-Core Elastomeric Yarns for Artificial Muscles and Strain Sensing2016In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086XArticle in journal (Refereed)
    Abstract [en]

    Highly stretchable, actuatable, electrically conductive knitted textiles based on Spandex (SPX)/CNT (carbon nanotube) composite yarns were prepared by an integrated knitting procedure. SPX filaments were continuously wrapped with CNT aerogel sheets and supplied directly to an interlocking circular knitting machine to form the three-dimensional electrically conductive and stretchable textiles. By adjusting the SPX/CNT feed ratio, the fabric electrical conductivities could be tailored in the range of 870 to 7092 S/m. The electrical conductivity depended on tensile strain, with a linear and largely hysteresis-free resistance change occurring on loading and unloading between 0 and 80% strain. Electrothermal heating of the stretched fabric caused large tensile contractions of up to 33%, and generated a gravimetric mechanical work capacity during contraction of up to 0.64 kJ/kg and a maximum specific power output of 1.28 kW/kg, which far exceeds that of mammalian skeletal muscle. The knitted textile provides the combination of strain sensing and the ability to control dimensions required for smart clothing that simultaneously monitors the wearer's movements and adjusts the garment fit or exerts forces or pressures on the wearer, according to needs. The developed processing method is scalable for the fabrication of industrial quantities of strain sensing and actuating smart textiles.

  • 32.
    Forro, Csaba
    et al.
    Swiss Fed Inst Technol, Switzerland.
    Demko, Laszlo
    Swiss Fed Inst Technol, Switzerland.
    Weydert, Serge
    Swiss Fed Inst Technol, Switzerland.
    Voros, Janos
    Swiss Fed Inst Technol, Switzerland.
    Tybrandt, Klas
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering. Swiss Fed Inst Technol, Switzerland.
    Predictive Model for the Electrical Transport within Nanowire Networks2018In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 12, no 11, p. 11080-11087Article in journal (Refereed)
    Abstract [en]

    Thin networks of high aspect ratio conductive nanowires can combine high electrical conductivity with excellent optical transparency, which has led to a widespread use of nanowires in transparent electrodes, transistors, sensors, and flexible and stretchable conductors. Although the material and application aspects of conductive nanowire films have been thoroughly explored, there is still no model which can relate fundamental physical quantities, like wire resistance, contact resistance, and nanowire density, to the sheet resistance of the film. Here, we derive an analytical model for the electrical conduction within nanowire networks based on an analysis of the parallel resistor network. The model captures the transport characteristics and fits a wide range of experimental data, allowing for the determination of physical parameters and performance-limiting factors, in sharp contrast to the commonly employed percolation theory. The model thus constitutes a useful tool with predictive power for the evaluation and optimization of nanowire networks in various applications.

    The full text will be freely available from 2019-11-06 15:02
  • 33. Frederiksen, Thomas
    et al.
    Munuera, C
    Ocal, C
    Brandbyge, Mads
    Paulsson, Magnus
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Sanches-Portal, D
    Arnau, A
    Exploring the Tilt-Angle Dependence of Electron Tunneling across Molecular Junctions of Self-Assembled Alkanethiols2009In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 3, no 8, p. 2073-2080Article in journal (Refereed)
    Abstract [en]

    Electronic transport mechanisms in molecular junctions are investigated by a combination of first-principles calculations and current-voltage measurements of several well-characterized structures. We study self-assembled layers of alkanethiols grown on Au(111) and form tunnel junctions by contacting the molecular layers with the tip of a conductive force microscope. Measurements done under low-load conditions permit us to obtain reliable tilt-angle and molecular length dependencies of the low-bias conductance through the alkanethiol layers. The observed dependence on tilt-angle is stronger for the longer molecular chains. Our calculations confirm the observed trends and explain them as a result of two mechanisms, namely, a previously proposed intermolecular tunneling enhancement as well as a hitherto overlooked tilt-dependent molecular gate effect.

  • 34. Freedman, Kevin J.
    et al.
    Haq, Syed Raza
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Fletcher, Michael R.
    Foley, Joe P.
    Jemth, Per
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Edel, Joshua B.
    Kim, Min Jun
    Nonequilibrium Capture Rates Induce Protein Accumulation and Enhanced Adsorption to Solid-State Nanopores2014In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 8, no 12, p. 12238-12249Article in journal (Refereed)
    Abstract [en]

    Single molecule capturing of analytes using an electrically biased nanopore is the fundamental mechanism in which nearly all nanopore experiments are conducted. With pore dimensions being on the order of a single molecule, the spatial zone of sensing only contains approximately a zeptoliter of volume. As a result, nanopores offer high precision sensing within the pore but provide little to no information about the analytes outside the pore. In this study, we use capture frequency and rate balance theory to predict and study the accumulation of proteins at the entrance to the pore. Protein accumulation is found to have positive attributes such as capture rate enhancement over time but can additionally lead to negative effects such as long-term blockages typically attributed to protein adsorption on the surface of the pore. Working with the folded and unfolded states of the protein domain PDZ2 from SAP97, we show that applying short (e.g., 3-25 s in duration) positive voltage pulses, rather than a constant voltage, can prevent long-term current blockades (i.e., adsorption events). By showing that the concentration of proteins around the pore can be controlled in real time using modified voltage protocols, new experiments can be explored which study the role of concentration on single molecular kinetics including protein aggregation, folding, and protein binding.

  • 35.
    Gannon, Greg
    et al.
    Tyndall National Institute, University College Cork.
    Greer, James C.
    Tyndall National Institute, University College Cork.
    Larsson, Andreas
    Thompson, Damien J.
    Tyndall National Institute, University College Cork.
    Molecular dynamics study of naturally occurring defects in self-assembled monolayer formation2010In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 4, no 2, p. 921-932Article in journal (Refereed)
    Abstract [en]

    One of the major challenges for nanofabrication, in particular microcontact printing (μ-CP), is the control of molecular diffusion, or "ink spreading", for the creation of nanopatterns with minimized "smudging"at pattern boundaries. In this study, fully atomistic computer simulations were used to measure the impact of naturally occurring domain boundaries on the diffusion of excess alkanethiol ink molecules on printed alkanethiol self-assembled monolayers (SAM). A periodic unit cell containing approximately one million atoms and with a surface area of 56 nm×55 nm was used to model a hexadecanethiol SAM on Au(111), featuring SAM domain boundaries and a range of concentrations of excess hexadecanethiol ink molecules diffusing on top. This model was simulated for a total of approximately 80 ns of molecular dynamics. The simulations reveal that domain boundaries impede the diffusion of excess ink molecules and can, in some cases, permanently trap excess inks. There is competition between ink spreading and ink trapping, with the ink/SAM interaction strongly dependent on both the ink concentration and the SAM orientation at domain boundaries. SAM defects thus provide potential diffusion barriers for the control of excess ink spreading, and simulations also illustrate atom-scale mechanisms for the repair of damaged areas of the SAM via self-healing. The ability of domain boundaries to trap excess ink molecules is accounted for using an accessible volume argument, and trapping is discussed in relation to experimental efforts to reduce molecular spreading on SAMs for the creation of ultrahigh resolution nanopatterns

  • 36.
    Gao, Feng
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Li, Zhe
    University of Cambridge, England.
    Wang, Jianpu
    University of Cambridge, England.
    Rao, Akshay
    University of Cambridge, England.
    Howard, Ian A.
    University of Cambridge, England.
    Abrusci, Agnese
    University of Cambridge, England.
    Massip, Sylvain
    University of Cambridge, England.
    McNeill, Christopher R.
    University of Cambridge, England.
    Greenham, Neil C.
    University of Cambridge, England.
    Trap-Induced Losses in Hybrid Photovoltaics2014In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 8, no 4, p. 3213-3221Article in journal (Refereed)
    Abstract [en]

    We investigate the loss mechanisms in hybrid photovoltaics based on blends of poly(3-hexylthiophene) with CdSe nanocrystals of various sizes. By combining the spectroscopic and electrical measurements on working devices as well as films, we identify that high trap-mediated recombination is responsible for the loss of photogenerated charge carriers in devices with small nanocrystals. In addition, we demonstrate that the reduced open-circuit voltage for devices with small nanocrystals is also caused by the traps.

  • 37.
    Gooth, Johannes
    et al.
    University of Hamburg, Germany ; IBM Research-Zurich, Switzerland.
    Zierold, Robert
    University of Hamburg, Germany.
    Sergelius, Philip
    University of Hamburg, Germany.
    Hamdou, Bacel
    University of Hamburg, Germany.
    Garcia, Javier
    IFW Dresden, Germany.
    Damm, Christine
    IFW Dresden, Germany.
    Rellinghaus, Bernd
    IFW Dresden, Germany.
    Pettersson, Håkan Jan
    Lund University ; Halmstad University.
    Pertsova, Anna
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Canali, Carlo M.
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Borg, Mattias
    IBM Research-Zurich, Switzerland.
    Nielsch, Kornelius
    University of Hamburg, Germany ; IFW Dresden, Germany.
    Local Magnetic Suppression of Topological Surface States in Bi2Te3 Nanowires2016In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 10, no 7, p. 7180-7188Article in journal (Refereed)
    Abstract [en]

    Locally induced, magnetic order on the surface of a topological insulator nanowire could enable room-temperature topological quantum devices. Here we report on the realization of selective magnetic control over topological surface states on a single facet of a rectangular Bi2Te3 nanowire via a magnetic insulating Fe3O4 substrate. Low-temperature magnetotransport studies provide evidence for local time-reversal symmetry breaking and for enhanced gapping of the interfacial 1D energy spectrum by perpendicular magnetic-field components, leaving the remaining nanowire facets unaffected. Our results open up great opportunities for development of dissipation-less electronics and spintronics.

  • 38.
    Gooth, Johannes
    et al.
    Institute of Nanostructure and Solid State Physics, Universität Hamburg, Hamburg, Germany & IBM Research-Zurich, Rüschlikon, Switzerland.
    Zierold, Robert
    Institute of Nanostructure and Solid State Physics, Universität Hamburg, Hamburg, Germany.
    Sergelius, Philip
    Institute of Nanostructure and Solid State Physics, Universität Hamburg, Hamburg, Germany.
    Hamdou, Bacel
    Institute of Nanostructure and Solid State Physics, Universität Hamburg, Hamburg, Germany.
    Garcia, Javier
    Institute for Metallic Materials, IFW Dresden, Dresden, Germany.
    Damm, Christine
    Institute for Metallic Materials, IFW Dresden, Dresden, Germany.
    Rellinghaus, Bernd
    Institute for Metallic Materials, IFW Dresden, Dresden, Germany.
    Pettersson, Håkan
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), MPE-lab. Division of Solid State Physics and NanoLund, Lund University, Lund, Sweden.
    Pertsova, Anna
    Department of Physics and Electrical Engineering, Linnaeus University, Kalmar, Sweden.
    Canali, Carlo
    Department of Physics and Electrical Engineering, Linnaeus University, Kalmar, Sweden.
    Borg, Mattias
    IBM Research-Zurich, Rüschlikon, Switzerland.
    Nielsch, Kornelius
    Institute of Nanostructure and Solid State Physics, Universität Hamburg, Hamburg, Germany & Institute for Metallic Materials, IFW Dresden, Dresden, Germany.
    Local Magnetic Suppression of Topological Surface States in Bi2Te3 Nanowires2016In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 10, no 7, p. 7180-7188Article in journal (Refereed)
    Abstract [en]

    Locally induced, magnetic order on the surface of a topological insulator nanowire could enable room-temperature topological quantum devices. Here we report on the realization of selective magnetic control over topological surface states on a single facet of a rectangular Bi2Te3 nanowire via a magnetic insulating Fe3O4 substrate. Low-temperature magnetotransport studies provide evidence for local time-reversal symmetry breaking and for enhanced gapping of the interfacial 1D energy spectrum by perpendicular magnetic-field components, leaving the remaining nanowire facets unaffected. Our results open up great opportunities for development of dissipation-less electronics and spintronics. © 2016 American Chemical Society.

  • 39.
    Gracia-Espino, Eduardo
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics. Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Barzegar, Hamid Reza
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Sharifi, Tiva
    Yan, Aiming
    Zettl, Alex
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Fabrication of One-Dimensional Zigzag [6,6]-Phenyl-C-61-Butyric Acid Methyl Ester Nanoribbons from Two-Dimensional Nanosheets2015In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 9, no 10, p. 10516-10522Article in journal (Refereed)
    Abstract [en]

    One-dimensional (10) zigzag [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) nanoribbons are produced by folding two-dimensional ultrathin PCBM nanosheets in a simple solvent process. The unique 1D PCBM nanostructures exhibit uniform width of 3.8 +/- 0.3 nm, equivalent to four PCBM molecules, and lengths of 20-400 nm. These nanoribbons show well-defined crystalline structure, comprising PCBM molecules in a hexagonal arrangement without trapped solvent molecules. First-principle calculations and detailed experimental characterization provide an insight into the structure and formation mechanism of the 1D PCBM nanoribbons. Given their dimensions and physical properties, we foresee that these nanostructures should be ideal as acceptor material in organic solar cells.

  • 40.
    Gusak, Viktoria
    et al.
    Chalmers University of Technology.
    Kasemo, Bengt
    Chalmers University of Technology.
    Hägglund, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. Chalmers University of Technology.
    Thickness dependence of plasmonic charge carrier generation in ultrathin a-Si:H layers for solar cells2011In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 5, no 8, p. 6218-6225Article in journal (Refereed)
  • 41.
    Hamedi, Mahiar M.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Hajian, Alireza
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Fall, Andreas B.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Håkansson, Karl
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Salajkova, Michaela
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Highly Conducting, Strong Nanocomposites Based on Nanocellulose-Assisted Aqueous Dispersions of Single-Wall Carbon Nanotubes2014In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 8, no 3, p. 2467-2476Article in journal (Refereed)
    Abstract [en]

    It is challenging to obtain high-quality dispersions of single-wall nanotubes (SWNTs) in composite matrix materials, in order to reach the full potential of mechanical and electronic properties. The most widely used matrix materials are polymers, and the route to achieving high quality dispersions of SWNT is mainly chemical functionalization of the SWNT. This leads to increased cost, a loss of strength and lower conductivity. In addition full potential of colloidal self-assembly cannot be fully exploited in a polymer matrix. This may limit the possibilities for assembly of highly ordered structural nanocomposites. Here we show that nanofibrillated cellulose (NFC) can act as an excellent aqueous dispersion agent for as-prepared SWNTs, making possible low-cost exfoliation and purification of SWNTs with dispersion limits exceeding 40 wt %. The NFC:SWNT dispersion may also offer a cheap and sustainable alternative for molecular self-assembly of advanced composites. We demonstrate semitransparent conductive films, aerogels and anisotropic microscale fibers with nanoscale composite structure. The NFC:SWNT nanopaper shows increased strength at 3 wt % SWNT, reaching a modulus of 133 GPa, and a strength of 307 MPa. The anisotropic microfiber composites have maximum conductivities above 200 S cm(-1) and current densities reaching 1400 A cm(-2).

  • 42.
    Hasan, Saad A
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Rigueur, John L
    Harl, Robert R
    Krejci, Alex J
    Gonzalo-Juan, Isabel
    Rogers, Bridget R
    Dickerson, James H
    Transferable Graphene Oxide Films with Tunable Microstructures.2010In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 4, no 12, p. 7367-7372Article in journal (Refereed)
    Abstract [en]

    This report describes methods to produce large-area films of graphene oxide from aqueous suspensions using electrophoretic deposition. By selecting the appropriate suspension pH and deposition voltage, films of the negatively charged graphene oxide sheets can be produced with either a smooth "rug" microstructure on the anode or a porous "brick" microstructure on the cathode. Cathodic deposition occurs in the low pH suspension with the application of a relatively high voltage, which facilitates a gradual change in the colloids' charge from negative to positive as they adsorb protons released by the electrolysis of water. The shift in the colloids' charge also gives rise to the brick microstructure, as the concurrent decrease in electrostatic repulsion between graphene oxide sheets results in the formation of multilayered aggregates (the "bricks"). Measurements of water contact angle revealed the brick films (79°) to be more hydrophobic than the rug films (41°), a difference we attribute primarily to the distinct microstructures. Finally, we describe a sacrificial layer technique to make these graphene oxide films free-standing, which would enable them to be placed on arbitrary substrates.

  • 43. He, Yuhui
    et al.
    Tsutsui, Makusu
    Scheicher, Ralph H.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Bai, Fan
    Taniguchi, Masateru
    Kawai, Tomoji
    Thermophoretic Manipulation of DNA Translocation through Nanopores2013In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 7, no 1, p. 538-546Article in journal (Refereed)
    Abstract [en]

    Manipulating DNA translocation through nanopore is one crucial requirement for new ultrafast sequencing methods in the sense that the polymers have to be denatured, unraveled, and then propelled through the pore with very low speed. Here we propose and theoretically explore a novel design to fulfill the demands by utilizing cross-pore thermal gradient. The high temperature in the cis reservoir is expected to transform double-stranded DNA into single strands and that temperature would also prevent those single strands from intrastrand base-pairing, thus, achieving favorable polymer conformation for the subsequent translocation and sequencing. Then, the substantial temperature drop across the pore caused by the thermal-insulating membrane separating cis and trans chambers would stimulate thermophoresis of the molecules through nanopores. Our theoretical evaluation shows that the DNA translocation speeds will be orders smaller than the electrophoretic counterpart, while high capture rate of DNA Into nanopore Is maintained, both of which would greatly benefit the sequencing.

  • 44.
    Huang, Bingru
    et al.
    South China Normal Univ, South China Acad Adv Optoelect, Ctr Opt & Electromagnet Res, Guangdong Prov Key Lab Opt Informat Mat & Technol, Guangzhou 510006, Guangdong, Peoples R China.
    Bergstrand, Jan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Experimental Biomolecular Physics.
    Duan, Sai
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Zhan, Qiuqiang
    South China Normal Univ, South China Acad Adv Optoelect, Ctr Opt & Electromagnet Res, Guangdong Prov Key Lab Opt Informat Mat & Technol, Guangzhou 510006, Guangdong, Peoples R China.
    Widengren, Jerker
    KTH, School of Engineering Sciences (SCI), Applied Physics, Experimental Biomolecular Physics.
    Ågren, Hans
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Liu, Haichun
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Overtone Vibrational Transition-Induced Lanthanide Excited-State Quenching in Yb3+/Er3+-Doped Upconversion Nanocrystals2018In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 12, p. 10572-10575Article in journal (Refereed)
  • 45.
    Jahn, Burkhard O.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Ottosson, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Physical Organic Chemistry.
    Galperin, Michael
    Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, United States.
    Fransson, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Organic Single Molecular Structures for Light Induced Spin-Pump Devices2013In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 7, no 2, p. 1064-1071Article in journal (Refereed)
    Abstract [en]

    We present theoretical results on molecular structures for realistic spin-pump applications. Taking advantage of the electron spin resonance concept, we find that interesting candidates constitute triplet biradicals with two strongly spatially and energetically separated singly occupied molecular orbitals (SOMOs). Building on earlier reported stable biradicals, particularly bis(nitronyl nitroxide) based biradicals, we employ density functional theory to design a selection of potential molecular spin-pumps which should be persistent at ambient conditions. We estimate that our proposed molecular structures will operate as spin-pumps using harmonic magnetic fields in the MHz regime and optical fields in the infrared to visible light regime.

  • 46. Jana, Avijit
    et al.
    Nguyen, Kim Truc
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Zhu, Pengcheng
    Tan, Nguan Soon
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Zhao, Yanli
    Perylene-Derived Single-Component Organic Nanoparticles with Tunable Emission: Efficient Anticancer Drug Carriers with Real-Time Monitoring of Drug Release2014In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 8, no 6, p. 5939-5952Article in journal (Refereed)
    Abstract [en]

    An organic nanoparticle-based drug delivery system with high drug loading efficacy (similar to 79 wt %) was developed using a perylene-derived photoremovable protecting group, namely, perylene-3,4,9,10-tetrayltetramethanol (Pe(OH)(4)). The anticancer drug chlorambucil was protected by coupling with Pe(OH)(4) to form photocaged nanoparticles (Pe(OH)(4)). The photorelease mechanism of chlorambucil from the Pe(Cbl)(4) conjugate was investigated experimentally by high-resolution mass spectrometry and theoretically by density functional theory calculations. The Pe(Cbl)(4) nanoparticles perform four important roles: (i) a nanocarrier for drug delivery, (ii) a phototrigger for drug release, (iii) a fluorescent chromophore for cell imaging, and (iv) a photoswitchable fluorophore for real-time monitoring of drug release. Tunable emission of the perylene-derived nanoparticles was demonstrated by comparing the emission properties of the Pe(OH)(4) and Pe(Cbl)(4) nanoparticles with perylene-3-ylmethanol. These nanoparticles were subsequently employed in cell imaging for investigating their intracellular localization. Furthermore, the in vivo toxicity of the Pe(OH)(4) nanoparticles was investigated using the mouse model. Histological tissue analysis of five major organs, i.e., heart, kidney, spleen, liver, and lung, indicates that the nanoparticles did not show any obvious damage to these major organs under the experimental conditions. The current research presents a successful example of integrating multiple functions into single-component organic nanoparticles for drug delivery.

  • 47. Karabulut, E.
    et al.
    Pettersson, T.
    RISE, Innventia.
    Ankerfors, M.
    RISE, Innventia.
    Wågberg, L.
    Adhesive layer-by-layer films of carboxymethylated cellulose nanofibril-dopamine covalent bioconjugates inspired by marine mussel threads2012In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, no 6, p. 4731-4739Article in journal (Refereed)
  • 48.
    Karabulut, Erdem
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Pettersson, Torbjörn
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Ankerfors, Mikael
    Material Processes, Innventia AB, Stockholm, Sweden.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Adhesive Layer-by-Layer Films of Carboxymethylated Cellulose Nanofibril Dopamine Covalent Bioconjugates Inspired by Marine Mussel Threads2012In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 6, no 6, p. 4731-4739Article in journal (Refereed)
    Abstract [en]

    The preparation of multifunctional films and coatings from sustainable, low-cost raw materials has attracted considerable interest during the past decade. In this respect, cellulose-based products possess great promise due not only to the availability of large amounts of cellulose in nature but also to the new classes of nanosized and well-characterized building blocks of cellulose being prepared from trees or annual plants. However, to fully utilize the inherent properties of these nanomaterials, facile and also sustainable preparation routes are needed. In this work, bioinspired hybrid conjugates of carboxymethylated cellulose nanofibrils (CNFC) and dopamine (DOPA) have been prepared and layer-by-layer (LbL) films of these modified nanofibrils have been built up in combination with a branched polyelectrolyte, polyethyleneimine (PEI), to obtain robust, adhesive, and wet-stable nanocoatings on solid surfaces. It is shown that the chemical functionalization of CNFCs with DOPA molecules alters their conventional properties both in liquid dispersion and at the interface and also influences the LbL. film formation by reducing the electrostatic interaction. Although the CNFC-DOPA conjugates show a lower colloidal stability in aqueous dispersions due to charge suppression, it was possible to prepare the LbL films through the consecutive deposition of the building blocks. Adhesive forces between muttilayer films prepared using chemically functionalized CNFCs and a silica probe are much stronger in the presence of Fe3+ than those between a multilayer film prepared from unmodified nanofibrils and a silica probe. The present work demonstrates a facile way to prepare chemically functionalized cellulose nanofibrils whereby more extended applications can produce novel cellulose-based materials with different functionalities.

  • 49.
    Klechikov, Alexey
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Talyzin, Alexandr V.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Comment on "Nanohole-Structured and Palladium-Embedded 3D Porous Graphene for Ultrahigh Hydrogen Storage and CO Oxidation Multifunctionalities"2016In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 10, no 10, p. 9055-9056Article in journal (Refereed)
  • 50.
    Krstic, Vojislav
    et al.
    Univ Dublin Trinity Coll, Sch Phys.
    Ewels, Christopher P
    Univ Nantes, CNRS.
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Ferreira, Mauro S
    Univ Dublin Trinity Coll, Sch Phys.
    Janssens, Anne M
    Delft Univ Technol.
    Stephan, Odile
    Univ Paris 11, LPS.
    Glerup, Marianne
    Univ Oslo, Dept Chem.
    Indirect magnetic coupling in light-element-doped single-walled carbon nanotubes2010In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 4, no 9, p. 5081-5086Article in journal (Refereed)
    Abstract [en]

    Single-walled carbon nanotubes substitutionally doped with the light-element phosphorus are synthesized and are investigated by electrical and nuclear magnetic resonance measurements. Decreased spin lattice relaxation times compared to undoped tubes point toward enhanced spin-sensitive scattering. Temperature dependence of the zero-bias conductance shows step-like features, a signature of scattering from a very low density (few sites per nanotube) of localized spin moments at oxidized phosphorus sites, consistent with density functional calculations. This supports recent predictions that localized magnetic moments must be indirectly magnetically coupled through the nanotube conduction electrons.

123 1 - 50 of 122
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