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  • 1. Aaboud, M.
    et al.
    Kastanas, Konstatinos A.
    KTH, School of Engineering Sciences (SCI), Physics.
    Lund-Jensen, Bengt
    KTH, School of Engineering Sciences (SCI), Physics.
    Ohm, Christian
    KTH, School of Engineering Sciences (SCI), Physics.
    Ripellino, Giulia
    KTH, School of Engineering Sciences (SCI), Physics.
    Sidebo, P. Edvin
    KTH, School of Engineering Sciences (SCI), Physics.
    Strandberg, Jonas
    KTH, School of Engineering Sciences (SCI), Physics.
    L.Zwalinski,
    et. al.,
    Search for an invisibly decaying Higgs boson or dark matter candidates produced in association with a Z boson in pp collisions at s=13 TeV with the ATLAS detector2018In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 776, p. 318-337Article in journal (Refereed)
    Abstract [en]

    A search for an invisibly decaying Higgs boson or dark matter candidates produced in association with a leptonically decaying Z boson in proton–proton collisions at s=13 TeV is presented. This search uses 36.1 fb−1 of data collected by the ATLAS experiment at the Large Hadron Collider. No significant deviation from the expectation of the Standard Model backgrounds is observed. Assuming the Standard Model ZH production cross-section, an observed (expected) upper limit of 67% (39%) at the 95% confidence level is set on the branching ratio of invisible decays of the Higgs boson with mass mH=125 GeV. The corresponding limits on the production cross-section of the ZH process with the invisible Higgs boson decays are also presented. Furthermore, exclusion limits on the dark matter candidate and mediator masses are reported in the framework of simplified dark matter models. 

  • 2. Aaboud, M.
    et al.
    Kastanas, Konstatinos A.
    KTH, School of Engineering Sciences (SCI), Physics.
    Lund-Jensen, Bengt
    KTH, School of Engineering Sciences (SCI), Physics.
    Ohm, Christian
    KTH, School of Engineering Sciences (SCI), Physics.
    Ripellino, Giulia
    KTH, School of Engineering Sciences (SCI), Physics.
    Sidebo, P. Edvin
    KTH, School of Engineering Sciences (SCI), Physics.
    Strandberg, Jonas
    KTH, School of Engineering Sciences (SCI), Physics.
    Zwalinski, L.
    et.al.,
    Measurement of differential cross sections of isolated-photon plus heavy-flavour jet production in pp collisions at s=8 TeV using the ATLAS detector2018In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, p. 295-317Article in journal (Refereed)
    Abstract [en]

    This Letter presents the measurement of differential cross sections of isolated prompt photons produced in association with a b-jet or a c-jet. These final states provide sensitivity to the heavy-flavour content of the proton and aspects related to the modelling of heavy-flavour quarks in perturbative QCD. The measurement uses proton–proton collision data at a centre-of-mass energy of 8 TeV recorded by the ATLAS detector at the LHC in 2012 corresponding to an integrated luminosity of up to 20.2 fb−1. The differential cross sections are measured for each jet flavour with respect to the transverse energy of the leading photon in two photon pseudorapidity regions: |ηγ|<1.37 and 1.56<|ηγ|<2.37. The measurement covers photon transverse energies 25<ET γ<400 GeV and 25<ET γ<350 GeV respectively for the two |ηγ| regions. For each jet flavour, the ratio of the cross sections in the two |ηγ| regions is also measured. The measurement is corrected for detector effects and compared to leading-order and next-to-leading-order perturbative QCD calculations, based on various treatments and assumptions about the heavy-flavour content of the proton. Overall, the predictions agree well with the measurement, but some deviations are observed at high photon transverse energies. The total uncertainty in the measurement ranges between 13% and 66%, while the central γ+b measurement exhibits the smallest uncertainty, ranging from 13% to 27%, which is comparable to the precision of the theoretical predictions.

  • 3.
    Almlöf, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Faculty of Mathematics and Science.
    Hydrogen bond studies. 71. Ab initio calculation of the vibrational structure and equilibrium geometry in HF2 and DF21972In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 17, no 1, p. 49-52Article in journal (Refereed)
    Abstract [en]

    MO LCAO SCF calculations have been performed to investigate the molecular astructure and vibrational spectrum of the bifluoride ion in its normal and deuterated form. The potential energy for nuclear motions has been evaluated as a function of the molecular degrees of freedom, taking only linear geometries into account. The vibrational Schrödinger equation has been solved by expanding the vibrational part of the total wavefunction as a sum of products of linear harmonic-oscillator eigenfunctions. The calculated properties are in good agreement with experiments, and even the minute effects of deuteration are well reproduced.

  • 4.
    Andersson, Mattias
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Inganäs , Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    From short to long - Optical and electrical transients in photovoltaic bulk heterojunctions of polyfluorene/fullerenes2009In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 357, no 1-3, p. 120-123Article in journal (Refereed)
    Abstract [en]

    We combine results from transient optical absorption in a bulk heterojunction polymer donor/fullerene acceptor material, obtained in the optical range as well as in the THz range, with results from electrical transients after a short light pulse, to present a unified interpretation of the transport of charge after the very first act of photoinduced charge transfer. We find that the mobility of charges is initially very high, but dramatically reduced with time, to arrive at values three orders of magnitude lower. We show that this can be understood as a consequence of the transport of hot charges by hopping through the density of states, from higher to lower energies.

  • 5.
    Anselmo, Ana Sofia
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Dzwilewski, Andrzej
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Svensson, Krister
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Moons, Ellen
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Photodegradation of the electronic structure of PCBM and C60 films in air2016In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 652, p. 220-224Article in journal (Refereed)
    Abstract [en]

    Fullerenes are common electron acceptors in organic solar cells. Here the photostability in air of the electronic structures of spin-coated PCBM ([6,6]-phenyl-C61-butyric acid methyl ester) and evaporated C60 films are studied using ultraviolet photoelectron spectroscopy (UPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. After exposing these materials in air to simulated sunlight, the filled and empty molecular orbitals are strongly altered, indicating that the conjugated π-system of the C60-cage has degraded. Even a few minutes in normal lab light induces changes. These results stress the importance of protecting fullerene-based films from light and air during processing, operation, and storage.

  • 6. Aquilante, Francesco
    et al.
    Jensen, K. P.
    Roos, Björn O.
    The allyl radical revisited: a theoretical study of the electronic spectrum.2003In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 380, no 5-6, p. 689-698Article in journal (Refereed)
    Abstract [en]

    In this Letter, we report the electronic spectrum of the allyl radical, obtained with multiconfigurational perturbation theory (MS-CASPT2). The assignment of the spectrum is in accordance with experiment to within 0.2 eV. We have computed the complete first Rydberg series and the beginning of the second Rydberg series. A new valence-excited B-2(1) state has been found which has hitherto been hidden by Rydberg transitions. A rationalisation of the electronic spectrum is provided in terms of resonance forms in ground and excited states. This model shows that while a multiconfigurational wavefunction is necessary to qualitatively model the system, the large ionic character of the valence electronic states makes an accurate treatment of the dynamical correlation necessary for a quantitative description of the spectrum.

  • 7. Aquilante, Francesco
    et al.
    Pedersen, Thomas Bondo
    Quartic scaling evaluation of canonical scaled opposite spin second-order Moller-Plesset correlation energy using Cholesky decompositions.2007In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 449, no 4-6, p. 354-357Article in journal (Refereed)
    Abstract [en]

    The scaled opposite spin second-order Moller-Plesset (SOS-MP2) energy expression is reformulated using Cholesky decomposition of the amplitude matrix. The resulting algorithm requires an auxiliary basis or Cholesky representation of the two-electron integrals and shows fourth-order scaling with system size. Based on an analysis of operation counts, we estimate that the present approach is computationally advantageous compared to the analogous fourth-order algorithms that employ Laplace transforms.

  • 8. Barnes, Leslie A
    et al.
    Lindh, Roland
    Department of Theoretical Chemistry, Lund University.
    Symmetry breaking in O+4: an application of the Brueckner coupled-cluster method1994In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 223, no 3, p. 207-214Article in journal (Refereed)
    Abstract [en]

    A recent calculation of the antisymmetric stretch frequency for the rectangular structure of quartet O4+ using the QCISD(T) method gave a value of 3710 cin-1. This anomalous frequency is shown to be a consequence of symmetry-breaking effects, which occur even though the QCISD(T) solution derived from a delocalized SCF reference function lies energetically well below the two localized (symmetry-broken) solutions at the equilibrium geometry. The symmetry breaking is almost eliminated at the CCSD level of theory, but the small remaining symmetry-breaking effects are magnified at the CCSD (T) level of theory so that the antisymmetric stretch frequency is still significantly in error. The Brueckner coupled-cluster method, however, leads to a symmetrical solution which is free of symmetry-breaking effects, with an antisymmetric stretch frequency of 1322 cm-1, in good agreement with our earlier calculations using the CASSCF/CASSI method.

  • 9.
    Baryshnikov, Glib V.
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. V. D. Kuznetsov Siberian Physical-Technical Institute at National Research Tomsk State University, Russian Federation.
    Minaev, Boris F.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. V. D. Kuznetsov Siberian Physical-Technical Institute at National Research Tomsk State University, Russian Federation.
    Baryshnikova, A. A.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Anion-induced exchange interactions in binuclear complexes of Cu(II) with flexible hexadentate bispicolylamidrazone ligands2016In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 661, p. 48-52Article in journal (Refereed)
    Abstract [en]

    Two recently synthesized copper(II) complexes with spacer-armed bispicolylamidrazone ligands have been theoretically studied at the density functional theory (DFT) level accounting for empirical dispersion correction and intrinsic anionic environment by perchlorate ions. The exchange parameter between the open-shell singlet and triplet states of the studied complexes has been estimated by broken symmetry DFT calculations. The mechanism of spin-spin exchange interaction between the unpaired electrons via the σ-bond aliphatic chain (Gusev et al., 2015) is confirmed. Instead, a anion-induced mechanism is proposed which means that the anionic grid participates in the exchange interaction between the unpaired electrons.

  • 10. Baudin, M.
    et al.
    Wojcik, M.
    Hermansson, Kersti
    KTH, Superseded Departments, Biotechnology.
    Palmqvist, A. E. C.
    Muhammed, Mamoun
    KTH, Superseded Departments, Materials Science and Engineering.
    MD simulations of a doped ceria surface - very large surface ion motion2001In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 335, no 06-maj, p. 517-523Article in journal (Refereed)
    Abstract [en]

    Mean-square displacements (MSDs) and individual-ion square-displacements (ISDs) for the different constituents in Ca-doped CeO2(0 1 1) slabs at 300 K have been studied as a function of depth from the surface. Constant pressure-constant temperature MD simulations were used. The MSDs are 2-3 times larger at the surface than in the bulk, but ISDs as large as ca. 150 times the surface MSD value were observed during short-time periods for anions next to an anion vacancy at the surface. The chemical implications of this kind of motion are important, since transient structural distortions of this magnitude will lead to large electron re-distributions.

  • 11. Bauer, C.
    et al.
    Boschloo, Gerrit
    Mukhtar, E.
    Hagfeldt, A.
    Ultrafast relaxation dynamics of charge carriers relaxation in ZnO nanocrystalline thin films2004In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 387, no 03-jan, p. 176-181Article in journal (Refereed)
    Abstract [en]

    Ultrafast spectroscopy has been used to study the relaxation processes of charge carriers in ZnO nanocrystalline thin films. A broad red-IR absorption band linked to shallowly trapped electrons was observed by spectroelectrochemical measurements. Femtosecond transient absorption data revealed multiexponential decays of the charge carriers with time constants ranging from 1 to 400 ps. The decay profile of the signal shows a probe wavelength dependence. This effect is assigned to the trapping (localisation) of nonequilibrium charge carriers which occurs on a time scale of similar to1 ps. The recombination of shallowly trapped electrons with deeply trapped holes, determined by single-photon counting, mainly occurs in 400 ps.

  • 12. Behzadi, Hadi
    et al.
    Esrafili, D
    Beheshtian, Javad
    Hadipour, L
    van der Spoel, David
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    A density functional study of N-15 chemical shielding tensors in quinolines2009In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 476, no 4-6, p. 196-200Article in journal (Refereed)
    Abstract [en]

    DFT calculations were carried out to characterize the N-15 shielding tensors in quinolines. This computational study is intended to shed light on the differences between two groups of quinolines: series A (7-chloro 4-aminoalkyls quinolines) and series B (quinolines, 3-, 5-, 6-, 8-amino quinolines and 4,8-dichloro quinoline). Unlike the quinolines in series B, the series A quinolines show considerable beta-hematin inhibition activity which is essential for quinoline-based drugs. The results show that the substitution position significantly affects the sigma(11) and sigma(22) components of N-15 shielding tensors of quinolines. The N-15 shielding components are noticeably different for the two series and can be related to their ability to interact with hematin. (C) 2009 Published by Elsevier B. V.

  • 13.
    Belghit, R.
    et al.
    Univ BadjiMokhtar, Dept Phys, Lab LESIMS, BP 12, Annaba 23000, Algeria..
    Belkhir, H.
    Univ BadjiMokhtar, Dept Phys, Lab LESIMS, BP 12, Annaba 23000, Algeria..
    Heciri, D.
    Univ BadjiMokhtar, Dept Phys, Lab LESIMS, BP 12, Annaba 23000, Algeria..
    Bououdina, M.
    Univ Bahrain, Coll Sci, Dept Phys, POB 32038, Sakheer, Bahrain..
    Kadri, M. T.
    Univ BadjiMokhtar, Dept Phys, Lab LESIMS, BP 12, Annaba 23000, Algeria..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    First principles study of structural, mechanical and electronic properties of the ternary alkali metal oxides KNaO and RbNaO2018In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 706, p. 684-693Article in journal (Refereed)
    Abstract [en]

    The structural, mechanical and electronic properties of the ternary inter-alkali metal oxides KNaO and RbNaO compounds are investigated by using first principle calculations. The structural parameters and atomic positions are in agreement with the experimental values. The bulk, shear and Young moduli, Poisson's ratio, Lame coefficients and Debye temperature have been calculated. The elastic parameters indicate that these compounds have ductile behavior. The calculated band structures indicate that KNaO and RbNaO have an indirect energy band gap. The charge density distributions reveal an anionic character. This theoretical study is likely to stimulate future experimental researches.

  • 14. Belyanin, Maxim L.
    et al.
    Stepanova, Elena V.
    Valiev, Rashid R.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. National Research Tomsk Polytechnic University, Russian Federation.
    Filimonov, Victor D.
    Usov, Vladimir Y.
    Borodin, Oleg Y.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Design, synthesis and evaluation of a new Mn - Contrast agent for MR imaging of myocardium based on the DTPA-phenylpentadecanoic acid complex2016In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 665, p. 111-116Article in journal (Refereed)
    Abstract [en]

    In the present paper we describe the first synthesis and evaluation of a novel Mn (II) complex (DTPA-PPDA Mn (II)) which contains a C-15 fatty acid moiety that has high affinity to the heart muscle. The complexation energy of DTPA-PPDA Mn (II) evaluated by quantum chemistry methodology indicates that it essentially exceeds the corresponding value for the known DTPA Mn (II) complex. Molecular docking revealed that the affinity of the designed complex to the heart-type transport protein H-FABP well exceeds that of lauric acid. Phantom experiments in low-field MRI the designed contrast agent provides MR imaging comparable to gadopentetic acid.

  • 15.
    Bergersen, Henrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Abu-samha, M.
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Marinho, Ricardo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Céolin, Denis
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Öhrwall, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Sæthre, L. J.
    Tchaplyguine, M.
    Børve, K. J.
    Svensson, Svante
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    First observation of vibrations in core-level photoelectron spectra of free neutral molecular clusters2006In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 429, no 1-3, p. 109-113Article in journal (Refereed)
    Abstract [en]

    Core-level photoelectron spectra of free neutral methane clusters have been recorded. These spectra exhibit well-resolved surface and bulk features as well as vibrational fine structure. The vibrational structure in the cluster signal is well reproduced by a theoretical model that assumes independent contributions from inter- and intramolecular modes. The intramolecular contribution to the vibrational line-shape is taken to be equal to that of the monomer in the gas phase, while the intermolecular part is simplified to line broadening. An estimate of the cluster size has been made on the basis of the observed surface-to-bulk intensity ratio.

  • 16.
    Berggren, Magnus
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Bergman, Peder
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Fagerström, Jan
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Andersson, Mats
    Chalmers Tekniska Högskola.
    Weman, Helge
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Granström, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Wennerström, O
    Chalmers Tekniska Högskola.
    Hjertberg, T
    Chalmers Tekniska Högskola.
    Controlling inter-chain and intra-chain excitations of a poly(thiophene) derivative in thin films1999In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 304, no 1-2, p. 84-90Article in journal (Refereed)
    Abstract [en]

    The decay of photoexcitations in polythiophene chains has been studied in solid solutions of the polymer from room temperature to 4 K. A strong blue shift of the emission spectrum is observed in the polymer blend, as compared to the homopolymer. Dispersion of the polythiophene suppresses the non-radiative processes, which are suggested to be correlated to close contacts of polymer chains. Quantum chemistry modeling of the excited state distributed on two chains corroborate this conclusion.

  • 17. Bernhardsson, Anders
    et al.
    Lindh, Roland
    Department of Theoretical Chemistry, Lund University.
    Karlström, Gunnar
    Roos, Björn O
    Direct self-consistent reaction field with Pauli repulsion: Solvation effects on methylene peroxide1996In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 251, no 3-4, p. 141-149Article in journal (Refereed)
    Abstract [en]

    The properties of methylene peroxide in the gas phase and water have been examined. The solution effects have been modeled with a cavity. To make it possible to optimize the geometry of the cavity, we have added an approximate description of the Pauli repulsion between the solvent and the solute. An efficient direct implementation of the calculation of multicenter multipole operators is also described. We have applied the method to calculate the electric properties of methylene peroxide, a system that is characterized by its near degeneracy between a biradical and a zwitterionic state. As expected, it is shown that solvent effects will stabilize the ionic configuration, resulting in a considerably weakened OO bond and an increased double bond character in the CO bond. The theoretical study has been performed using the multiconfigurational (CAS) SCF method and second-order perturbation theory (CASPT2).

  • 18. Biglino, D.
    et al.
    Bonora, M.
    Volodin, A.
    Boreskov Institute of Catalysis, 630090 Novosibirsk, Russian Federation.
    Lund, Anders
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Chemical Physics .
    Pulsed EPR study of the (NO)2-Na+ triplet state adsorption complex2001In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 349, no 5-6, p. 511-516Article in journal (Refereed)
    Abstract [en]

    The (NO)2-Na+ triplet state complex stabilised in Na-A zeolites at low temperature was studied by pulsed EPR. The 3-pulse ESEEM spectra at 5 K were analysed by simulations in the time-domain, followed by Fourier transformation. The ESEEM was attributed to the interaction with Na+. The hyperfine coupling A(23Na)=(4.6, 4.6, 8.2) MHz and nuclear quadrupole Q(23Na)=(0.3, 0,3, -0.6) MHz tensors are of comparable magnitude as in the NO-Na+ complex determined earlier. The complexes are proposed to be either pairs of NO-Na+ or ON-Na+-NO.

  • 19. Birgerson, J.
    et al.
    Keil, M.
    Luo, Y.
    Theoretical Chemistry, Royal Institute of Technology, S-100 44 Stockholm, Sweden.
    Svensson, S.
    Department of Physics, Uppsala University, S-751 21 Uppsala, Sweden.
    Agren, H.
    Ågren, H., Theoretical Chemistry, Royal Institute of Technology, S-100 44 Stockholm, Sweden.
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    A study of the electronic structure of ethylenedioxythiophene in gas phase using NEXAFS and quantum chemical calculations2004In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 392, no 1-3, p. 100-104Article in journal (Refereed)
    Abstract [en]

    Near-edge X-ray absorption fine structure spectroscopy spectra of ethylenedioxythiophene has been recorded in gas phase at the carbon K-edge, sulphur L-edge and oxygen, K-edge. The experimental data has been interpreted with the help of a modified density functional code deMon. The good agreement between the calculated spectra and the measured one allows us to assign all observed resonances. The existence of p* resonances in both the measured and the calculated OK-edge adsorption spectrum demonstrate that the delocalized p-system of the thiophene part of the molecule is extended up to the oxygen atoms of the molecule. © 2004 Elsevier B.V. All rights reserved.

  • 20. Birgerson, J.
    et al.
    Keil, M.
    Luo, Yi
    KTH, Superseded Departments, Biotechnology.
    Svensson, S.
    Ågren, Hans
    KTH, Superseded Departments, Biotechnology.
    Salaneck, W. R.
    A study of the electronic structure of ethylenedioxythiophene in gas phase using NEXAFS and quantum chemical calculations2004In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 392, no 1-3, p. 100-104Article in journal (Refereed)
    Abstract [en]

    Near-edge X-ray absorption fine structure spectroscopy spectra of ethylenedioxythiophene has been recorded in gas phase at the carbon K-edge, sulphur L-edge and oxygen, K-edge. The experimental data has been interpreted with the help of a modified density functional code deMon. The good agreement between the calculated spectra and the measured one allows us to assign all observed resonances. The existence of pi* resonances in both the measured and the calculated OK-edge adsorption spectrum demonstrate that the delocalized pi-system of the thiophene part of the molecule is extended up to the oxygen atoms of the molecule.

  • 21.
    Birgerson, Jonas
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Keil, M
    Luo, Y
    Ågren, H
    Salaneck, W.R
    A study of the electronic structure of ethylenedioxythiophene in gasphase using NEXAFS and quantum chemical calculations2004In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, no 392, p. 100-104Article in journal (Refereed)
  • 22. Bittererova, M.
    et al.
    Brinck, Tore
    KTH, Superseded Departments, Chemistry.
    Ostmark, H.
    Theoretical study of the singlet electronically excited states of N-42001In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 340, no 06-maj, p. 597-603Article in journal (Refereed)
    Abstract [en]

    Vertical excitation energies for the lowest eleven singlet states of T-d N-4 were calculated using the TD-DFT method with the B3LYP functional, and at the EOM-CCSD level of theory. The vertical excitation energies for the five lowest-lying excited states were also obtained using the state-averaged CASSCF, CASPT2, CASPT3, and MRCI + Q methods. Our results show that the five lowest-lying states are of valence character. EOM-CCSD/d-aug-cc-pVTZ calculations predict that there are two weakly allowed optical transitions of T-2 symmetry at 10.44 and 10.82 eV. The transition to the third T-2 state, which is predicted to be at 10.89 eV, has an oscillator strength about one order of magnitude higher.

  • 23. Bittererova, M.
    et al.
    Ostmark, H.
    Brinck, Tore
    KTH, Superseded Departments, Chemistry.
    Ab initio study of the ground state and the first excited state of the rectangular (D-2h) N-4 molecule2001In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 347, no 03-jan, p. 220-228Article in journal (Refereed)
    Abstract [en]

    The dissociation pathway of D-2h N-4 has been investigated at the CASSCF level of theory. A new C-2v transition state to dissociation was found and characterized on the potential energy surface. The effective barrier of dissociation from D-2h N-4 to 2N(2) is estimated to 6.5 kcal/mol from MR-AQCCNTZ//CAS(12,12)/VTZ calculations. Vertical excitation energies and oscillator strengths for the lowest 20 singlet states of D-2h N-4 have been calculated using the EOM-CCSD method. The geometry of the first excited state B-1(3u), considered as the lowest optically accessible state, has been optimized and characterized at various computational levels. This state might be useful for detection of D-2h N-4 by means of laser-induced fluorescence (LIF) spectroscopy.

  • 24.
    Borg, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    A singlet mechanism for photodissociation of bromofluorobenzenes2007In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 436, no 1-3, p. 57-62Article in journal (Refereed)
    Abstract [en]

    The C-Br photo-fragmentation of bromo-3,5-difluorobenzene (Br-3,5-diFBz) has been investigated using ab initio methods. A reaction coordinate combining a carbon-bromine bond stretch and a bromine out-of-plane bending on the S1 surface has been found with an activation energy of 2.96 kcal/mol, compatible with the observed picosecond time scale.

  • 25.
    Borg, O. Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Karlsson, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Isomäki-Krondahl, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Davidsson, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Lunell, Sten
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Predissociation of Chlorobenzene, beyond the pseudo-diatomic model2008In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 456, no 4-6, p. 123-126Article in journal (Refereed)
    Abstract [en]

    Dissociation of chlorobenzene via the lowest singlet excited state has been investigated by means of pump-probe femtosecond spectroscopy and spin-orbit corrected ab initio quantum chemistry. We have found that the so far accepted model with a (1)pi pi* -> (3)pi/n sigma* reaction mechanism has to be amended. We suggest that the mechanism goes via a transition from (1)pi pi* to a pi sigma* state that is to 90% a singlet. Further, three nuclear degrees of freedom required to describe the dissociation have been defined.

  • 26. Boschloo, Gerrit
    et al.
    Hagfeldt, A.
    Photoinduced absorption spectroscopy of dye-sensitized nanostructured TiO22003In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 370, no 04-mar, p. 381-386Article in journal (Refereed)
    Abstract [en]

    Photoinduced absorption (PIA) spectroscopy was used to investigate dye-sensitized electrodes and solar cells under illumination conditions comparable to sunlight. In the absence of redox electrolyte, cis-Ru (dcbpy)(2)(NCS)(2)-sensitized nanostructured TiO2 films show a long-lived photoinduced charge-separation (oxidized dye molecules/injected electrons in TiO2), with a lifetime of about 10(-3) s under full sun illumination. The PIA spectrum of a complete dye-sensitized cell is due to electrons in TiO2 and iodine radicals (12) in the electrolyte. The lifetime of this charge-separated state at open-circuit conditions was determined to be 0.15 s (0.27 sun illumination).

  • 27.
    Braun, Slawomir
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry . Linköping University, The Institute of Technology.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry . Linköping University, The Institute of Technology.
    Fermi level pinning at interfaces with tetrafluorotetracyanoquinodimethane (F4-TCNQ): The role of integer charge transfer states2007In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 438, no 4-6, p. 259-262Article in journal (Refereed)
    Abstract [en]

    The energy level alignment of vacuum deposited molecular films of tetrafluorotetracyanoquinodimethane (F4-TCNQ) on various substrates has been studied by photoelectron spectroscopy. The interfaces studied span the work function range from 3.45 to 5.8 eV. In this range, the Fermi level of the substrate is pinned in proximity to LUMO level. This indicates that a charge transfer mechanism is responsible for the observed alignment scheme. The photoelectron emission study of sub-monolayer of F4-TCNQ revealed presence of electrons in the charge transfer states at the interface. In this context the electronic structure of neutral and negatively charged F4-TCNQ has been studied theoretically and by photoelectron spectroscopy.

  • 28.
    Brumboiu, Iulia
    et al.
    Department of Physics and Astronomy, Uppsala University.
    Anselmo, Ana Sofia
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Brena, Barbara
    Department of Physics and Astronomy, Uppsala University.
    Dzwilewski, Andrzej
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Svensson, Krister
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Moons, Ellen
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Near-edge X-ray Absorption Fine Structure Study of the C60-derivative PCBM2013In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 568-569, p. 130-134Article in journal (Refereed)
    Abstract [en]

    The fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester plays a key role for electron transport in polymer solar cells. We have studied the unoccupied molecular orbitals of PCBM by near edge X-ray absorption fine structure spectroscopy and were able to assign the main resonances to molecular moieties by comparison with calculated sum spectra of individual carbons. We analyzed specifically the origin of the high-energy shoulder to the first π-resonance and identified contributions from the lowest-energy transition of a specific carbon in the phenyl and from transitions to higher unoccupied orbitals of the unmodified carbons in the C60-cage.

  • 29.
    Brumboiu, Iulia E.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Anselmo, A. S.
    Brena, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Dzwilewski, A.
    Svensson, K.
    Moons, E.
    Near-edge X-ray absorption fine structure study of the C-60-derivative PCBM2013In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 568, p. 130-134Article in journal (Refereed)
    Abstract [en]

    The fullerene derivative [6,6]-phenyl-C-61-butyric acid methyl ester plays a key role for electron transport in polymer solar cells. We have studied the unoccupied molecular orbitals of PCBM by near edge X-ray absorption fine structure spectroscopy and were able to assign the main resonances to molecular moieties by comparison with calculated sum spectra of individual carbons. We analyzed specifically the origin of the high-energy shoulder to the first pi*-resonance and identified contributions from the lowest-energy transition of a specific carbon in the phenyl and from transitions to higher unoccupied orbitals of the unmodified carbons in the C-60-cage. 

  • 30.
    Brändas, Erkki
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Faculty of Mathematics and Science.
    Mårtensson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Faculty of Mathematics and Science.
    Wave function constructed from complex hybrids1969In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 3, no 5, p. 315-318Article in journal (Refereed)
    Abstract [en]

    The influence on the total wave function of an atomic basis consisting of complex hybrids is considered. The complex character of the wave function in the MO-LCAO scheme ss well as in the VB method is derived, and its consequences with respect to time reversal symmetry are discussed.

  • 31.
    Buc, D.
    et al.
    Slovak University of Technology.
    Stuchlikova, L.
    Slovak University of Technology.
    Helmersson, Ulf
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Chang, W.H.
    University of Western Ontario.
    Bello, I.
    City University of Hong Kong.
    Investigation of RuO2/4H-SiC Schottky diode contacts by deep level transient spectroscopy2006In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 429, no 4-6, p. 617-621Article in journal (Refereed)
    Abstract [en]

    Schottky diodes were prepared on n-type silicon carbide (4H-SiC) substrates by deposition of ruthenium dioxide contacts. Their electrical and electronic properties were investigated by current-voltage (I-V) and capacitance-voltage (C-V) methods, and deep level transient spectroscopy (DLTS). Five deep energy levels with thermal activation energies of approximately 0.27, 0.45, 0.56, 0.58 and 0.85 eV referenced to the conduction band minimum were revealed. The two energy levels at 0.56 and 0.85 eV are presumably induced by divacancies and the incorporation of ruthenium impurities into the SiC interfacial region. The Schottky diode structures are typical with a barrier height of 0.88 eV, and the I-V characteristics signify a saturation current of 10 pA with an ideality factor of 1.28.

  • 32. Buendia, E.
    et al.
    Galvez, F. J.
    Maldonado, Pablo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Sarsa, A.
    Dynamical correlation effects in the transition probability: A study for the atoms Li to Ar2012In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 548, p. 1-6Article in journal (Refereed)
    Abstract [en]

    Explicitly correlated wave functions constructed as a Jastrow correlation factor times a model function have been obtained for the ground and the first excited state of opposite parity of the atoms Li to Ar. Single and restricted multi-configuration model functions are employed. Line strength, oscillator strength and transition probabilities have been obtained. An analysis of the different correlation mechanisms considered, single particle excitations and dynamical correlations, on these quantities is carried out. All calculations have been done by using Variational Monte Carlo, except when no Jastrow is involved where calculations have been performed using the Optimized Effective Potential method. (C) 2012 Elsevier B. V. All rights reserved.

  • 33. Buendia, E.
    et al.
    Galvez, F. J.
    Maldonado, Pablo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Sarsa, A.
    Explicitly correlated wave functions for atoms and singly charged ions from Li through Sr: Variational and Diffusion Monte Carlo results2014In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 615, p. 21-25Article in journal (Refereed)
    Abstract [en]

    Total energies calculated from explicitly correlated wave functions for the ground state of the atoms Li to Sr and their singly charged anions and cations are obtained. Accurate all electron, non-relativistic Variational and Diffusion Monte Carlo energies are reported. The quality of the results, when comparing with exact estimations and experimental electron affinities and ionization potential is similar for all of the atoms studied. The parameterization of the explicitly correlated wave functions for all of the atomic systems studied is provided.

  • 34. Buendia, E.
    et al.
    Galvez, F. J.
    Maldonado, Pablo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Sarsa, A.
    Quantum Monte Carlo ionization potential and electron affinity for transition metal atoms2013In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 559, p. 12-17Article in journal (Refereed)
    Abstract [en]

    Non-relativistic all-electron Quantum Monte Carlo ground state energies of the neutral atoms K to Zn and positive and negative ions are calculated starting from explicitly correlated wave functions. The accuracy obtained for these atoms and ions in the fourth period is similar to that reached for those in the second and third periods. For the atoms and ions for which the 4s-4p near degeneracy effect can be important a restricted multi-configuration expansion has been employed. Ionization potentials and electron affinities have been calculated showing a good agreement with the experimental values.

  • 35.
    Carlegrim, Elin
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Kanciurzewska, Anna
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    de Jong, Michel P
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Fahlman, Mats
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    The unoccupied electronic structure of the semi-conducting room temperature molecular magnet V(TCNE)22008In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 452, no 1-3, p. 173-177Article in journal (Refereed)
    Abstract [en]

    The unoccupied electronic structure of the organic-based magnet V(TCNE)x (TCNE = tetracyanoethylene, x~2) has been studied with near edge x-ray absorption fine structure (NEXAFS) and with photoelectron spectroscopy (PES). By studying V(TCNE)x upon sodium-doping, the electron-accepting state, i.e. the lowest unoccupied molecular orbital (LUMO) of V(TCNE)x was shown mainly to be localized on (TCNE)--units in contrast to the hole-accepting state, i.e. the highest occupied molecular orbital (HOMO), which previously was assigned primarily to be V(3d)-derived. This study also showed that there are trap states for electron transport located below the (TCNE)2- level, likely leading to decreased electron mobility.

  • 36. Carniato, S.
    et al.
    Taieeb, R.
    Guillemin, R.
    Journel, L.
    Simon, M.
    Gel'mukhanov, Faris
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    K-L resonant X-ray Raman scattering as a tool for potential energy surface mapping2007In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 439, no 06-apr, p. 402-406Article in journal (Refereed)
    Abstract [en]

    With help of theoretical calculations, we demonstrate that original pump-probe experiments, using IR laser as a pump and K-L X-ray Raman scattering as a probe, offer a powerful tool to map core-excited potential energy curves with very high energy resolution, beyond vibrational and lifetime limitations.

  • 37. Carravetta, V.
    et al.
    Ågren, Hans
    KTH, Superseded Departments, Biotechnology.
    An ab initio method for computing multi-atom resonant photoemission2002In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 354, no 02-jan, p. 100-108Article in journal (Refereed)
    Abstract [en]

    We present an ab initio method for computing multi-atom resonant photoemission (MARPE) in molecules and use this method to investigate the possibility of having a sizable MARPE effect. The MARPE cross section is obtained by making multi-center expansions of both the dipole matrix element - direct emission - and the hamiltonian matrix element between the resonant state and the autoionizing states - resonant emission. We show by sample calculations that the resonant contribution exhibits a strong distance dependence of the atoms participating in the MARPE process, and that it is energy dependent and element specific for the neighboring atoms. The ratio of resonant MARPE and direct photoionization cross sections is found to amount to less than one percent which probably makes the molecular MARPE effect difficult to apply in practice.

  • 38.
    Carvalho, Alexandra
    et al.
    Department of Physics, I3N, University of Aveiro, Campus Santiago.
    Rayson, Mark
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Briddon, Patrick R.
    Electrical, Electronic and Computer Engineering, University of Newcastle upon Tyne.
    Manzhos, Sergei
    Department of Mechanical Engineering, Faculty of Engineering, National University of Singapore.
    Effect of the adsorption of ethylene carbonate on Si surfaces on the Li insertion behavior2013In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 585, p. 157-161Article in journal (Refereed)
    Abstract [en]

    Effects of the ethylene carbonate (EC) solvent on Li insertion and diffusion in Si anodes are studied using density functional theory. On both (100) and (111) reconstructed surfaces of Si, a semi-dissociated (SD) configuration of EC is stable and most favorable for Li insertion, lowering its barrier by up to 0.2 eV vs a clean surface. The less stable molecular adsorption has little effect on Li insertion and diffusion, while the surface ketone formed by dissociating the SD configuration at a cost of 0.6 eV has a strong detrimental effect on Li insertion, increasing its barrier by up to 0.4 eV.

  • 39. Cava, Carlos E.
    et al.
    Possagno, Ricardo
    Schnitzler, Mariane C.
    Roman, Paulo C.
    Oliveira, Marcela M.
    Lepiensky, Carlos M.
    Zarbin, Aldo J. G.
    Roman, Lucimara S.
    Iron- and iron oxide-filled multi-walled carbon nanotubes: Electrical properties and memory devices2007In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 444, no 4-6, p. 304-308Article in journal (Refereed)
    Abstract [en]

    Electrical and morphological properties of neat iron- and iron oxide-filled multi-walled carbon nanotubes and its dispersion with a semiconducting polymer were investigated. The electrical properties of these carbon nanotubes changed significantly when exposed to different atmospheres. The current voltage characteristics of the films formed from the dispersions were obtained from planar devices with metallic electrodes. These devices were used as gas sensor and as memory devices where the writing, reading and erasing can be done electrically.

  • 40.
    Chatterjee, S
    et al.
    Swiss Federal Institute for Materials Science and Technology, Empa.
    Wang, J.W.
    National Cheng Kung University, Taiwan.
    Kuo, W.S.
    Feng Chia University, Taiwan.
    Tai, N.H.
    National Tsing Hua University, Hsinchu, Taiwan.
    Salzmann, C.
    University College London, London, UK.
    Li, W.L.
    Hollertz, Rebecca
    Swiss Fed Labs Mat Sci & Technol Empa, Lab Funct Polymers, Switzerland.
    Nüesch, F.
    Chu, B.T.T.
    Mechanical reinforcement and thermal conductivity in expanded graphene nanoplatelets reinforced epoxy composites2012In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 531, p. 6-10Article in journal (Refereed)
    Abstract [en]

    Influence of reinforcements on mechanical and thermal properties of graphene nanoplatelets/epoxy composites is investigated. Amine functionalized expanded graphene nanoplatelets (EGNPs) were dispersed within epoxy resins using high-pressure processor followed by three roll milling. Functionality on the EGNPs was confirmed with FTIR and micro-Raman spectroscopy. Bending and nano-mechanical testing was performed on the composites. Incorporation of EGNPs improved the flexural modulus and hardness of the composite and increased fracture toughness by up to 60%. Marked improvement was observed in thermal conductivity of the composites reaching 36% at 2 wt.% loading. Functionalized EGNPs exhibited significant improvements indicating favorable interaction at EGNPs/polymer interface.

  • 41. Chatterjee, Sanjukta
    et al.
    Wang, J W
    Kuo, W S
    Tai, N H
    Salzmann, C
    Li, W L
    Hollertz, R
    Nüesch, F A
    Chu, B T T
    Mechanical reinforcement and thermal conductivity in expanded graphene nanoplatelets reinforced epoxy composites2012In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 531, p. 6-10Article in journal (Refereed)
    Abstract [en]

    Influence of reinforcements on mechanical and thermal properties of graphene nanoplatelets/epoxy com-posites is investigated. Amine functionalized expanded graphene nanoplatelets (EGNPs) were dispersed within epoxy resins using high-pressure processor followed by three roll milling. Functionality on the EGNPs was confirmed with FTIR and micro-Raman spectroscopy. Bending and nano-mechanical testingwas performed on the composites. Incorporation of EGNPs improved the flexural modulus and hardness of the composite and increased fracture toughness by up to 60%. Marked improvement was observed inthermal conductivity of the composites reaching 36% at 2 wt.% loading. Functionalized EGNPs exhibited significant improvements indicating favorable interaction at EGNPs/polymer interface.

  • 42. Chattopadhyaya, Mausumi
    et al.
    Natarajan Arul, Murgan
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Alam, Md. Mehboob
    Chakrabarti, Swapan
    Spatial spin-charge separation in neutral endohedral metallofullerene: A combined restricted open-shell MP2 and Car-Parrinello molecular dynamics study2013In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 557, p. 71-75Article in journal (Refereed)
    Abstract [en]

    We present the first theoretical evidence of the unusual separation of spin and charge degrees of freedom of electron in a neutral endohedral metallofullerene, Sc@C-50. To demystify its origin, we have performed computation at the level of ROMP2 in combination with Car-Parrinello molecular dynamics at 300 K on a series of Sc@C-n. Our inspection reveals that a sharp fall of electron correlation in Sc@C-50 makes the system so sensitive that, to avoid additional Pauli repulsion, Sc leaves the charge component of the solitary 3d electron to C-50 keeping the spin density over its own.

  • 43.
    Chen, Hao
    et al.
    Kunming University of Science & Technology, CHI.
    Li, Xuechao
    Kunming University of Science & Technology, CHI.
    Wan, Rundong
    Kunming University of Science & Technology, CHI.
    Kao-Walter, Sharon
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mechanical Engineering.
    Lei, Ying
    Anhui University of Technology, CHI.
    Leng, Chongyan
    Kunming University of Science & Technology, CHI.
    A DFT study on modification mechanism of (N,S) interstitial co-doped rutile TiO22018In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 695, p. 8-18Article in journal (Refereed)
    Abstract [en]

    To obtain a more efficient (N,S) co-doping scheme, we systematically analyze the geometrical parameters, density of states, charge densities, relative dielectric functions and UV–Vis absorption spectra for pure, N/S substitution/interstitial doped and (N,S) substitution/interstitial co-doped TiO2 by using density functional calculations. Compared with (N,S) substitution co-doping, (N,S) interstitial co-doping TiO2 exhibits a more obvious red-shift of absorption edge, because of the band gap is further reduced. Furthermore, there are shallow impurity levels coupling with the top of valence band. The calculated UV–Vis absorption spectra illustrate that (N,S) interstitial co-doping TiO2 has much higher photocatalytic activity in the visible light region. © 2018

  • 44.
    Chen, Tao
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Leiden Observatory, Leiden University, PO Box 9513, NL 2300 RA Leiden, The Netherlands.
    Zhen, J.
    Wang, Ying
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Linnartz, H.
    Tielens, A. G. G. M.
    From planes to bowls: Photodissociation of the bisanthenequinone cation2018In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 692, p. 298-303Article in journal (Refereed)
    Abstract [en]

    We present a combined experimental and theoretical study of the photodissociation of the bisanthenequinone (C28H12O2) cation, Bq+. The experiments show that, upon photolysis, the Bq+ cation does not dehydrogenate, but instead fragments through the sequential loss of the two neutral carbonyl groups, causing the formation of five-membered carbon cycles. Quantum chemical calculations confirm this Bq+ → [Bq - CO]+ → [Bq - 2CO]+ sequence as the energetically most favorable reaction pathway. For the first CO loss, a transition state with a barrier of ∼3.2 eV is found, substantially lower than the lowest calculated H loss dissociation pathway (∼4.9 eV). A similar situation applies for the second CO loss channel (∼3.8 eV vs. ∼4.7 eV), but where the first dissociation step does not strongly alter the planar PAH geometry, the second step transforms the molecule into a bowl-shaped one. 

  • 45.
    Cronstrand, P.
    et al.
    Theoretical Chemistry, Royal Institute of Technology, SCFAB, SE-106 91 Stockholm, Sweden.
    Luo, Y.
    Theoretical Chemistry, Royal Institute of Technology, SCFAB, SE-106 91 Stockholm, Sweden.
    Norman, Patrick
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Computational Physics .
    Agren, H.
    Ågren, H., Theoretical Chemistry, Royal Institute of Technology, SCFAB, SE-106 91 Stockholm, Sweden.
    Ab initio calculations of three-photon absorption2003In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 375, no 1-2, p. 233-239Article in journal (Refereed)
    Abstract [en]

    We present large scale ab initio calculations of three-photon absorption of a series of dithienothiophene based charge transfer molecules using response theory within the random phase approximation. The structure-to-property relations obtained for the three-photon absorption cross-sections are discussed and compared with those for one- and two-photon absorption. © 2003 Published by Elsevier Science B.V.

  • 46. Cronstrand, P.
    et al.
    Luo, Yi
    KTH, Superseded Departments, Biotechnology.
    Ågren, Hans
    KTH, Superseded Departments, Biotechnology.
    Generalized few-state models for two-photon absorption of conjugated molecules2002In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 352, no 04-mar, p. 262-269Article in journal (Refereed)
    Abstract [en]

    We present three- and four-state models for two-photon absorption (TPA) cross-sections generalized to include dipolar direction information and polarization effects of the laser beam. By introducing an effective dipole moment which incorporates the directions of the transition dipole moments and the influence of additionally strongly coupled excited states we can distinguish between different effects leading to enhanced two-photon absorption.

  • 47.
    Cronstrand, Peter
    et al.
    KTH, Superseded Departments, Biotechnology.
    Luo, Yi
    KTH, Superseded Departments, Biotechnology.
    Norman, P.
    Ågren, Hans
    KTH, Superseded Departments, Biotechnology.
    Ab initio calculations of three-photon absorption2003In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 375, no 02-jan, p. 233-239Article in journal (Refereed)
    Abstract [en]

    We present large scale ab initio calculations of three-photon absorption of a series of dithienothiophene based charge transfer molecules using response theory within the random phase approximation. The structure-to-property relations obtained for the three-photon absorption cross-sections are discussed and compared with those for one- and two-photon absorption.

  • 48.
    de Almeida, Katia Júlia
    et al.
    Univ Fed Minas Gerais, Dept Quim.
    Cesar, Amary
    Univ Fed Minas Gerais, Dept Quim.
    Rinkevicius, Zilvinas
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Vahtras, Olav
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Modelling the visible absorption spectra of copper(II) acetylacetonate by density functional theory2010In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 492, no 1-3, p. 14-18Article in journal (Refereed)
    Abstract [en]

    Spin restricted open-shell Density Functional Theory calculations have been carried out by means of linear response theory to investigate the visible absorption spectrum of copper(II) acetylacetonate complex, Cu(acac)(2). The 3d -> 3d transition energies and the influence of molecular structure and non-coordinating solvent on the spectra have been investigated. The obtained four 3d -> 3d transition energies accord well with the experimental data in the crystal phase. The presented results indicate that the experimentally observed four band structure of Cu(acac)(2) is of molecular nature, and not caused by factor-group splitting in the crystal environment as previously suggested.

  • 49. Derkatch, A.
    et al.
    Lundevall, C.
    Berg, Lars-Erik
    KTH, Superseded Departments, Physics.
    Royen, P.
    Lifetime measurements of the A (2)Pi state of BaCl using laser spectroscopy2000In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 332, no 04-mar, p. 278-282Article in journal (Refereed)
    Abstract [en]

    The lowest-lying radiative state of barium chloride has been studied by laser-induced fluorescence in the near-infrared wavelength region. The A (II1/2)-I-2 and A (II3/2)-I-2 states have been investigated in time-resolved experiments using a Ti:Sapphire laser. The zero pressure radiative lifetime measured for the e-levels of BaCl was 107 +/- 4 ns for the A (II1/2)-I-2 state and 101+/-6 ns for the A (II3/2)-I-2 state. The discrepancy between the corresponding transition moments is discussed.

  • 50. Dopieralski, Przemyslaw D.
    et al.
    Burakowski, Andrzej
    Latajka, Zdzislaw
    Olovsson, Ivar
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Structural Chemistry.
    Hydration of NaHCO3, KHCO3, (HCO3-)(2), HCO3- and CO32- from molecular dynamics simulation and speed of sound measurements2011In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 507, no 1-3, p. 89-95Article in journal (Refereed)
    Abstract [en]

    Car-Parrinello molecular dynamics and acoustic method have been applied to determine the hydration of HCO3- and CO32- ions in aqueous solution. From CPMD simulations the hydration numbers are 5.3 and 8.5 for the HCO3- and CO32- ions, respectively. From speed of sound and density measurements the hydration numbers for HCO3- and CO32- are 5.5 and 10.2, respectively. Our attempt to answer the old question concerning the status of HCO3 in solution quite well support the earlier spectroscopic results that no (HCO3)(2) is present in the solution but the existence of the minor amount of dimers cannot be definitely excluded.

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