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  • 51.
    Holmberg, Anders
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Lindblom, Magnus
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Controlled electroplating for high-aspect-ratio zone plate fabrication2006In: Journal of Vacuum Science & Technology B, ISSN 1071-1023, E-ISSN 1520-8567, Vol. 24, no 6, p. 2592-2596Article in journal (Refereed)
    Abstract [en]

    The authors report a method for monitoring, control, and end-point detection of electroplating in nanostructures. The method is demonstrated on nickel plating into polymer molds, which is an important process in the fabrication of soft x-ray zone-plate diffractive optics. The lack of reproducibility presently limits the achievable nickel aspect ratio and, thus, reduces the zone-plate diffraction efficiency. The reported method provides reproducible plating via real-time control of the plating rate. It combines in situ light transmission measurements with current measurements to determine the thickness of the growing layer. The accuracy of the thickness prediction was better than ±4% (1) for 100–300  nm nickel layers. Furthermore, a slight change in the light transmission signal indicates when a gratinglike zone-plate structure is slightly overplated and the plating should be stopped. This end-point detection provides the optimal filling of high-aspect-ratio molds for improved diffraction efficiency.

  • 52.
    Holmberg, Anders
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lindblom, Magnus
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Reinspach, Julia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Bertilson, Michael
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Soft x-ray zone plate fabrication at KTH, Stockholm2009In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 186Article in journal (Refereed)
    Abstract [en]

    We present the status of our zone plate and test object fabrication processes along with the latest fabricated components. With our nickel process, zone plates with outermost zone width of 20 nm and zone height of 90 nm have been fabricated. A gold electroplating process has recently been introduced for the fabrication of test objects. The first result for gold gratings with 70 nm period and 135 nm height is shown.

  • 53.
    Holmberg, Anders
    et al.
    KTH, Superseded Departments, Physics.
    Rehbein, Stefan
    KTH, Superseded Departments, Physics.
    Hertz, Hans M.
    KTH, Superseded Departments, Physics.
    Nano-fabrication of condenser and micro zone plates for compact X-ray microscopy2004In: Microelectronic Engineering, ISSN 0167-9317, E-ISSN 1873-5568, Vol. 73/74, p. 639-643Article in journal (Refereed)
    Abstract [en]

    We demonstrate nano-fabrication of high-aspect ratio and high-spatial frequency diffractive X-ray optics with high uniformity for use in a laser-plasma-based compact water-window X-ray microscope. The structures are fabricated on 50 nm thin Si3N4-membranes using a three-layer resist scheme and 30 keV e-beam lithography in combination with reactive ion etching and nickel electroplating. The process is developed on solely commercially available resists and instruments. As examples, we demonstrate fabrication of micro-zone plates with outermost linewidths of 30 nm and an uniform zone height of 160 nm, and a 4.5 mm diameter condenser zone plate with 50-60 nm lines, fabricated by using stitched fields.

  • 54.
    Holmberg, Anders
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Reinspach, Julia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lindblom, Magnus
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Chubarova, Elena
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Bertilson, Michael
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    von Hofsten, Olov
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Nilsson, Daniel
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Selin, Mårten
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Larsson, Daniel
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Skoglund Lindberg, Peter
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lundstrom, Ulf
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Takman, Per
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Ulrich
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Towards 10-nm Soft X-Ray Zone Plate Fabrication2011Conference paper (Refereed)
    Abstract [en]

    In this paper the latest efforts to improve our nanofabrication process for soft x‐ray zone plates is presented. The resolving power, which is proportional to the smallest outermost zone width of the zone plate, is increased by introducing cold development of the electron beam resist that is used for the patterning. With this process we have fabricated Ni zone plates with 13‐nm outermost zone and shown potential for making 11‐nm half‐pitch lines in the electron beam resist. Maintaining the diffraction efficiency of the zone plate is a great concern when the outermost zone width is decreased. To resolve this problem we have developed the so‐called Ni‐Ge zone plate in which the zone plate is build up by Ni and Ge, resulting in an increase of the diffraction efficiency. In a proof‐of‐principle experiment with 25‐nm Ni‐Ge zone plates, we have shown a doubling of the diffraction efficiency. When combined with cold development, the Ni‐Ge process has been shown to work down to 16‐nm half‐pitch. It is plausible that further refinement of the process will make it possible to go to 10‐nm outermost zone widths.

  • 55. Hoppe, R.
    et al.
    Meier, V.
    Patommel, J.
    Seiboth, F.
    Lee, H. J.
    Nagler, B.
    Galtier, E. C.
    Arnold, B.
    Zastrau, U.
    Hastings, J.
    Nilsson, Daniel
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Uhlén, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Ulrich
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Schroer, C. G.
    Schropp, A.
    Full characterization of a focused wavefield with sub 100 nm resolution2013In: Advances In X-Ray Free-Electron Lasers II: Instrumentation, SPIE - International Society for Optical Engineering, 2013, p. 87780G-Conference paper (Refereed)
    Abstract [en]

    A hard x-ray free-electron laser (XFEL) provides an x-ray source with an extraordinary high peak-brilliance, a time structure with extremely short pulses and with a large degree of coherence, opening the door to new scientific fields. Many XFEL experiments require the x-ray beam to be focused to nanometer dimensions or, at least, benefit from such a focused beam. A detailed knowledge about the illuminating beam helps to interpret the measurements or is even inevitable to make full use of the focused beam. In this paper we report on focusing an XFEL beam to a transverse size of 125nm and how we applied ptychographic imaging to measure the complex wavefield in the focal plane in terms of phase and amplitude. Propagating the wavefield back and forth we are able to reconstruct the full caustic of the beam, revealing aberrations of the nano-focusing optic. By this method we not only obtain the averaged illumination but also the wavefield of individual XFEL pulses.

  • 56.
    Hultström, Jessica
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Manneberg, Otto
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Dopf, Katja
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Brismar, Hjalmar
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Proliferation and viability of adherent cells manipulated by standing-wave ultrasound in a microfluidic chip2007In: Ultrasound in Medicine and Biology, ISSN 0301-5629, E-ISSN 1879-291X, Vol. 33, p. 145-151Article in journal (Refereed)
    Abstract [en]

    Ultrasonic-standing-wave (USW) technology has potential to become a standard method for gentle and contactless cell handling in microfluidic chips. We investigate the viability of adherent cells exposed to USWs by studying the proliferation rate of recultured cells following ultrasonic trapping and aggregation of low cell numbers in a microfluidic chip. The cells form 2-D aggregates inside the chip and the aggregates are held against a continuous flow of cell culture medium perpendicular to the propagation direction of the standing wave. No deviations in the doubling time from expected values (24 to 48 h) were observed for COS-7 cells held in the trap at acoustic pressure amplitudes up to 0.85 MPa and for times ranging between 30 and 75 min. Thus, the results demonstrate the potential of ultrasonic standing waves as a tool for gentle manipulation of low cell numbers in microfluidic systems.

  • 57.
    Hultström, Jessica
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Manneberg, Otto
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Brismar, Hjalmar
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Proliferation and viability of COS-7 cells trapped by standing-wave ultrasound in a microfluidic chip2006In: Micro Total Analysis Systems - Proceedings of MicroTAS 2006 Conference, Japan Academic Association Inc , 2006, p. 449-451Conference paper (Refereed)
    Abstract [en]

    We study cell viability after ultrasonic-standing-wave trapping of low cell numbers in a microfluidic chip by recultivation of the trapped cells. The cell proliferation rate is estimated by counting of initial and final cell numbers and shows normal cell growth. The results demonstrate the potential of ultrasonic standing waves as a tool for gentle and long-term manipulation of low cell numbers in microfluidic systems.

  • 58.
    Hultström, Jessica
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Manneberg, Otto
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Towards gentle long-term cell manipulation in a microfluidic chip using ultrasonic standing wave technology2007In: Proc. 1st International Congress on Ultrasonics, 2007Conference paper (Refereed)
  • 59.
    Häggmark, Ilian
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Romell, Jenny
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lewin, Susanne
    Öhman, Caroline
    Hertz, Hans
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics. KTH, School of Engineering Sciences (SCI), Physics. KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Cellular-Resolution Imaging of Microstructures in Rat Bone using Laboratory Propagation-Based Phase-Contrast X-ray Tomography2018In: Microscopy and Microanalysis, 2018, Vol. 24, p. 368-369Conference paper (Refereed)
  • 60.
    Häggmark, Ilian
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vågberg, William
    Hertz, Hans
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Comparison of quantitative multi-material phase-retrieval algorithms in propagation-based phase-contrast X-ray tomography2017In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 25, no 26, p. 33543-33558Article in journal (Refereed)
    Abstract [en]

    Propagation-based phase-contrast X-ray imaging provides high-resolution, dose-efficient images of biological materials. A crucial challenge is quantitative reconstruction, referred to as phase retrieval, of multi-material samples from single-distance, and hence incomplete, data. In this work, the two most promising methods for multi-material samples, the parallel method, and the linear method, are analytically, numerically, and experimentally compared. Both methods are designed for computed tomography, as they rely on segmentation in the tomographic reconstruction. The methods are found to result in comparable image quality, but the linear method provides faster reconstruction. In addition, as already done for the parallel method, we show that the linear method provides quantitative reconstruction for monochromatic radiation.

  • 61.
    Häggmark, Ilian
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vågberg, William
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Biomedical Applications of Multi-Material Phase Retrieval in Propagation-Based Phase-Contrast Imaging2018In: Microscopy and Microanalysis, Cambridge University Press, 2018, Vol. 24, p. 370-371Conference paper (Refereed)
  • 62.
    Jansson, Per
    et al.
    KTH, Superseded Departments, Physics.
    Hansson, B. A. M.
    KTH, Superseded Departments, Physics.
    Hemberg, Oscar
    KTH, Superseded Departments, Physics.
    Otendal, Mikael
    KTH, Superseded Departments, Physics.
    Holmberg, Anders
    KTH, Superseded Departments, Physics.
    De Groot, Jaco
    KTH, Superseded Departments, Physics.
    Hertz, Hans
    KTH, Superseded Departments, Physics.
    Liquid-tin-jet laser-plasma extreme ultraviolet generation2004In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 84, no 13, p. 2556-2258Article in journal (Refereed)
    Abstract [en]

    We demonstrate the applicability of liquid-metal jets in vacuum as regenerative targets for laser-plasma generation of extreme ultraviolet (EUV) and soft x-ray radiation. This extends the operation of liquid jet laser-plasma,sources to high-temperature, high-Z, high-density, low-vapor-pressure materials with new spectral signatures. The system is demonstrated using tin (Sn) as the target due to its strong emission around lambdaapproximate to13 nm, which makes the material suitable for EUV lithography. We show a conversion efficiency of 2.5% into (2% BW x 2pi x sr) and report quantitative measurements of the ionic/atomic as well as particulate debris emission.

  • 63.
    Jansson, Per
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Ultich
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Liquid-nitrogen-jet laser-plasma source for compact soft x-ray microscopy2005In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 76, no 4, p. 043503-Article in journal (Refereed)
    Abstract [en]

    We describe a liquid-nitrogen-jet laser-plasma source with sufficient brightness, uniformity, stability, and reliability to be suitable for compact water-window soft x-ray transmission microscopy. A cooled capillary nozzle arrangement allows long-term operation and avoids previously reported jet instabilities. The source is quantitatively characterized by calibrated slit-grating spectroscopy and zone-plate imaging. The absolute photon number in the major spectral lines (lambda=2.48 nm and lambda=2.88 nm) is 1.0x10(12) photons/(pulsexsrxline). The source diameter is similar to 20 mu m (full width at half maximum) and the spatial stability is better than +/- 2 mu m. Within an area with uniformity of 20%, the average source brightness is 4x10(8) photons/(pulsexsrx mu m(2)xline), which allows operation of a compact soft x-ray transmission microscope with exposure times of a few minutes.

  • 64. Johansson, G. A.
    et al.
    Berglund, M.
    Eriksson, F.
    Birch, J.
    Hertz, Hans M.
    KTH, Superseded Departments, Physics.
    Compact soft x-ray reflectometer based on a line-emitting laser-plasma source2001In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 72, no 1, p. 58-62Article in journal (Refereed)
    Abstract [en]

    We describe a compact soft x-ray reflectometer for in-house characterization of water-window multilayer optics. The instrument is based on a line-emitting, liquid-jet, laser-plasma source in combination with angular scanning of the studied multilayer optics. With a proper choice of target liquid and thin-film filters, one or a few lines of well-defined wavelength dominate the spectrum and multilayer periods are measured with an accuracy of 0.003 nm using a multi-line calibration procedure. Absolute reflectivity may also be estimated with the instrument. The typical measurement time is currently 10 min. Although the principles of the reflectometer may be used in the entire soft x-ray and extreme ultraviolet range, the current instrument is primarily directed towards normal-incidence multilayer optics for water-window x-ray microscopy, and is thus demonstrated on W/B4C multilayers for this wavelength range.

  • 65.
    Kördel, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Arsana, Komang Gede Yudi
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Ulrich
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Stability investigation of a cryo soft x-ray microscope by fiber interferometry2020In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 91, no 2, article id 023701Article in journal (Refereed)
    Abstract [en]

    We present a stability investigation of the Stockholm laboratory cryo soft x-ray microscope. The microscope operates at a wavelength of 2.48 nm and can image biological samples at liquid-nitrogen temperatures in order to mitigate radiation damage. We measured the stability of the two most critical components, sample holder and optics holder, in vacuo and at cryo temperatures at both short and long time scales with a fiber interferometer. Results revealed vibrations in the kHz range, originating mainly from a turbo pump, as well as long term drifts in connection with temperature fluctuations. With improvements in the microscope, earlier stability issues vanished and close-to diffraction-limited imaging could be achieved. Moreover, our investigation shows that fiber interferometers are a powerful tool in order to investigate position-sensitive setups at the nanometer level.

  • 66.
    Kördel, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Dehlinger, Aurelie
    Technische Universität Berlin.
    Seim, Christian
    Technische Universität Berlin.
    Vogt, Ulrich
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Fogelqvist, Emelie
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Sellberg, Jonas A.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Stiel, Holger
    Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Berlin.
    Hertz, Hans
    KTH, Superseded Departments (pre-2005), Physics. KTH, School of Engineering Sciences (SCI), Physics. KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics. KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Laboratory water-window x-ray microscopyManuscript (preprint) (Other academic)
  • 67.
    Kördel, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Fogelqvist, Emelie
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Carannante, Valentina
    Department of Microbiology, Karolinska Institutet.
    Önfelt, Björn
    KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Reddy, Hemanth K. N.
    Department of Cell and Molecular Biology, Uppsala University.
    Okamoto, Kenta
    Department of Cell and Molecular Biology, Uppsala University.
    Svenda, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Sellberg, Jonas A.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans
    KTH, Superseded Departments (pre-2005), Physics. KTH, School of Engineering Sciences (SCI), Physics. KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics. KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Biological Laboratory X-ray Microscopy2018In: Microscopy and Microanalysis, Vol. 24, no S2, p. 346-347Article in journal (Refereed)
  • 68.
    Kördel, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Fogelqvist, Emelie
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Carannante, Valentina
    Karolinska Inst, Dept Microbiol Tumor & Cell Biol, S-17177 Solna, Sweden..
    Önfelt, Björn
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Reddy, Hemanth K. N.
    Uppsala Univ, Dept Cell & Mol Biol, Lab Mol Biophys, S-75124 Uppsala, Sweden..
    Svenda, Martin
    Uppsala Univ, Dept Cell & Mol Biol, Lab Mol Biophys, S-75124 Uppsala, Sweden..
    Sellberg, Jonas A.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Arsana, Komang G.Y.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Ulrich
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Biological Laboratory X-Ray Microscopy2019In: X-Ray Nanoimaging: Instruments and Methods IV / [ed] Lai, B Somogyi, A, SPIE - International Society for Optical Engineering, 2019, Vol. 11112, article id 111120TConference paper (Refereed)
    Abstract [en]

    Zone-plate-based soft x-ray microscopes operating in the water window allow high-resolution and high-contrast imaging of intact cells in their near-native state. Laboratory-source-based x-ray microscopes are an important complement to the accelerator-based instruments, providing high accessibility and allowing close integration with other cell-biological techniques. Here we present recent biological applications using the Stockholm laboratory water-window x-ray microscope, which is based on a liquid-nitrogen-jet laser-plasma source. Technical improvements to the microscope in the last few years have resulted in increased x-ray flux at the sample and significantly improved stability and reliability. In addition to this, vibrations in key components have been measured, analyzed and reduced to improve the resolution to 25 nm half-period. The biological applications include monitoring the development of carbon-dense vesicles in starving human embryonic kidney cells (HEK293T), imaging the interaction between natural killer (NK) cells and HEK293T target cells, and most recently studying a newly discovered giant DNA virus and the process of viral replication inside a host amoeba. All biological imaging was done on cryo-frozen hydrated samples in 2D and in some cases 3D.

  • 69.
    Kördel, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Svenda, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Reddy, Hemanth K. N.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics. Department of Cell and Molecular Biology, Uppsala University.
    Fogelqvist, Emelie
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hamawandi, Bejan
    KTH.
    Toprak, Muhammet
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. KTH, Superseded Departments (pre-2005), Materials Science and Engineering. KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration. KTH, School of Engineering Sciences (SCI), Applied Physics.
    Hertz, Hans
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics. KTH, Superseded Departments (pre-2005), Physics. KTH, School of Engineering Sciences (SCI), Physics. KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Sellberg, Jonas A.
    KTH, Superseded Departments (pre-2005), Physics. KTH, School of Engineering Sciences (SCI), Physics. KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics. KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Quantitative bioconversion in giant DNA virus infectionManuscript (preprint) (Other academic)
  • 70.
    Larsson, Daniel H.
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lundström, Ulf
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Westermark, U.
    Takman, Per
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Arsenian Henriksson, M.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Small-animal tomography with a liquid-metal-jet x-ray source2012In: Progress in Biomedical Optics and Imaging - Proceedings of SPIE, SPIE - International Society for Optical Engineering, 2012, Vol. 8313, p. 83130N-Conference paper (Refereed)
    Abstract [en]

    X-ray tomography of small animals is an important tool for medical research. For high-resolution x-ray imaging of few-cm-thick samples such as, e.g., mice, high-brightness x-ray sources with energies in the few-10-keV range are required. In this paper we perform the first small-animal imaging and tomography experiments using liquid-metal-jet-anode x-ray sources. This type of source shows promise to increase the brightness of microfocus x-ray systems, but present sources are typically optimized for an energy of 9 keV. Here we describe the details of a high-brightness 24-keV electron-impact laboratory microfocus x-ray source based on continuous operation of a heated liquid-In/Ga-jet anode. The source normally operates with 40 W of electron-beam power focused onto the metal jet, producing a 7×7 μm 2 FWHM x-ray spot. The peak spectral brightness is 4 × 10 9 photons/( s × mm 2 × mrad 2 × 0.1%BW) at the 24.2 keV In K α line. We use the new In/Ga source and an existing Ga/In/Sn source for high-resolution imaging and tomography of mice.

  • 71.
    Larsson, Daniel H.
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lundström, Ulf
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Westermark, Ulrica K.
    Arsenian Henriksson, Marie
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    First application of liquid-metal-jet sources for small-animal imaging: High-resolution CT and phase-contrast tumor demarcation2013In: Medical physics (Lancaster), ISSN 0094-2405, Vol. 40, no 2, p. 021909-Article in journal (Refereed)
    Abstract [en]

    Purpose: Small-animal studies require images with high spatial resolution and high contrast due to the small scale of the structures. X-ray imaging systems for small animals are often limited by the microfocus source. Here, the authors investigate the applicability of liquid-metal-jet x-ray sources for such high-resolution small-animal imaging, both in tomography based on absorption and in soft-tissue tumor imaging based on in-line phase contrast. Methods: The experimental arrangement consists of a liquid-metal-jet x-ray source, the small-animal object on a rotating stage, and an imaging detector. The source-to-object and object-to-detector distances are adjusted for the preferred contrast mechanism. Two different liquid-metal-jet sources are used, one circulating a Ga/In/Sn alloy and the other an In/Ga alloy for higher penetration through thick tissue. Both sources are operated at 40-50 W electron-beam power with similar to 7 mu m x-ray spots, providing high spatial resolution in absorption imaging and high spatial coherence for the phase-contrast imaging. Results: High-resolution absorption imaging is demonstrated on mice with CT, showing 50 mu m bone details in the reconstructed slices. High-resolution phase-contrast soft-tissue imaging shows clear demarcation of mm-sized tumors at much lower dose than is required in absorption. Conclusions: This is the first application of liquid-metal-jet x-ray sources for whole-body small-animal x-ray imaging. In absorption, the method allows high-resolution tomographic skeletal imaging with potential for significantly shorter exposure times due to the power scalability of liquid-metal-jet sources. In phase contrast, the authors use a simple in-line arrangement to show distinct tumor demarcation of few-mm-sized tumors. This is, to their knowledge, the first small-animal tumor visualization with a laboratory phase-contrast system.

  • 72.
    Larsson, Daniel H.
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Takman, Per A.C.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lundström, Ulf
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    A 24 keV liquid-metal-jet x-ray source for biomedical applications2011In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 82, no 12, p. 123701-Article in journal (Refereed)
    Abstract [en]

    We present a high-brightness 24-keV electron-impact microfocus x-ray source based on continuous operation of a heated liquid-indium/gallium-jet anode. The 30–70 W electron beam is magnetically focused onto the jet, producing a circular 7–13 μm full width half maximum x-ray spot. The measured spectral brightness at the 24.2 keV In Kα line is 3 × 109 photons/(s × mm2 × mrad2 × 0.1% BW) at 30 W electron-beam power. The high photon energy compared to existing liquid-metal-jet sources increases the penetration depth and allows imaging of thicker samples. The applicability of the source in the biomedical field is demonstrated by high-resolution imaging of a mammography phantom and a phase-contrast angiography phantom.

  • 73.
    Larsson, Daniel H.
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics. Stanford University, United States.
    Vågberg, William
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Yaroshenko, Andre
    Yildirim, Ali Oender
    Hertz, Hans
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    High-resolution short- exposure small-animal laboratory x-ray phase-contrast tomography2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 39074Article in journal (Refereed)
    Abstract [en]

    X-ray computed tomography of small animals and their organs is an essential tool in basic and preclinical biomedical research. In both phase-contrast and absorption tomography high spatial resolution and short exposure times are of key importance. However, the observable spatial resolutions and achievable exposure times are presently limited by system parameters rather than more fundamental constraints like, e.g., dose. Here we demonstrate laboratory tomography with few-ten mu m spatial resolution and few-minute exposure time at an acceptable dose for small-animal imaging, both with absorption contrast and phase contrast. The method relies on a magnifying imaging scheme in combination with a high-power small-spot liquid-metal-jet electron-impact source. The tomographic imaging is demonstrated on intact mouse, phantoms and excised lungs, both healthy and with pulmonary emphysema.

  • 74.
    Larsson, Jakob C.
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Shaker, Kian
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Focused anti-scatter grid for background reduction in x-ray fluorescence tomography2018In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 43, no 11, p. 2591-2594Article in journal (Refereed)
    Abstract [en]

    X-ray fluorescence (XRF) tomography is an emerging imaging technology with the potential for high spatial resolution molecular imaging. One of the key limitations is the background noise due to Compton scattering since it degrades the signal and limits the sensitivity. In this Letter, we present a linear focused anti-scatter grid that reduces the Compton scattering background. An anti-scatter grid was manufactured and evaluated both experimentally and theoretically with Monte Carlo simulations. The measurements showed a 31% increase in signal-to-background ratio, and simulations of an improved grid showed that this can easily be extended up to > 75%. Simulated tomographies using the improved grid show a large improvement in reconstruction quality. The anti-scatter grid will be important for in vivo XRF tomography since the background reduction allows for faster scan times, lower doses, and lower nanoparticle concentrations.

  • 75.
    Larsson, Jakob C.
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Carmen
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vågberg, William
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Toprak, Muhammet
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Dzieran, Johanna
    Arsenian-Henriksson, Marie
    Hertz, Hans
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    High-spatial-resolution x-ray fluorescence tomography with spectrally matched nanoparticles2018In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 63, p. 164001-Article in journal (Refereed)
    Abstract [en]

    Present macroscopic biomedical imaging methods provide either morphology with high spatial resolution (e.g. CT) or functional/molecular information with lower resolution (e.g. PET). X-ray fluorescence (XRF) from targeted nanoparticles allows molecular or functional imaging but sensitivity has so far been insufficient resulting in low spatial resolution, despite long exposure times and high dose. In the present paper, we show that laboratory XRF tomography with metal-core nanoparticles (NPs) provides a path to functional/molecular biomedical imaging with ~100 µm resolution in living rodents. The high sensitivity and resolution rely on the combination of a high-brightness liquid-metal-jet x-ray source, pencil-beam optics, photon-counting energy-dispersive detection, and spectrally matched NPs. The method is demonstrated on mice for 3D tumor imaging via passive targeting of in-house-fabricated molybdenum NPs. Exposure times, nanoparticle dose, and radiation dose agree well with in vivo imaging.

  • 76.
    Larsson, Jakob C.
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vågberg, William
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Carmen
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lundström, Ulf
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Larsson, Daniel H.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    High-spatial-resolution nanoparticle X-ray fluorescence tomography2016In: MEDICAL IMAGING 2016: PHYSICS OF MEDICAL IMAGING, 2016, article id 97831VConference paper (Refereed)
    Abstract [en]

    X-ray fluorescence tomography (XFCT) has potential for high-resolution 3D molecular x-ray bio-imaging. In this technique the fluorescence signal from targeted nanoparticles (NPs) is measured, providing information about the spatial distribution and concentration of the NPs inside the object. However, present laboratory XFCT systems typically have limited spatial resolution (>1 mm) and suffer from long scan times and high radiation dose even at high NP concentrations, mainly due to low efficiency and poor signal-to-noise ratio. We have developed a laboratory XFCT system with high spatial resolution (sub-100 mu m), low NP concentration and vastly decreased scan times and dose, opening up the possibilities for in-vivo small-animal imaging research. The system consists of a high-brightness liquid-metal-jet microfocus x-ray source, x-ray focusing optics and an energy-resolving photon-counting detector. By using the source's characteristic 24 keV line-emission together with carefully matched molybdenum nanoparticles the Compton background is greatly reduced, increasing the SNR. Each measurement provides information about the spatial distribution and concentration of the Mo nanoparticles. A filtered back-projection method is used to produce the final XFCT image.

  • 77. Legall, H.
    et al.
    Blobel, G.
    Stiel, H.
    Sandner, W.
    Seim, C.
    Takman, Per
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Martz, Dale H.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Selin, Mårten
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Ulrich
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Esser, D.
    Sipma, H.
    Luttmann, J.
    Höfffer, M.
    Hoffmann, H. D.
    Yulin, S.
    Feigl, T.
    Rehbein, S.
    Guttmann, P.
    Schneider, G.
    Wiesemann, U.
    Wirtz, M.
    Diete, W.
    Compact X-ray microscope for the water window based on a high brightness laser plasma source2012In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 20, no 16, p. 18362-18369Article in journal (Refereed)
    Abstract [en]

    We present a laser plasma based x-ray microscope for the water window employing a high-average power laser system for plasma generation. At 90 W laser power a brightness of 7.4 x 10(11) photons/(s x sr x mu m(2)) was measured for the nitrogen Ly alpha line emission at 2.478 nm. Using a multilayer condenser mirror with 0.3 % reflectivity 10(6) photons/(mu m(2) x s) were obtained in the object plane. Microscopy performed at a laser power of 60 W resolves 40 nm lines with an exposure time of 60 s. The exposure time can be further reduced to 20 s by the use of new multilayer condenser optics and operating the laser at its full power of 130 W.

  • 78. Legall, H.
    et al.
    Stiel, H.
    Blobel, G.
    Seim, C.
    Baumann, J.
    Yulin, S.
    Esser, D.
    Hoefer, M.
    Wiesemann, U.
    Wirtz, M.
    Schneider, G.
    Rehbein, S.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    A compact laboratory transmission X-ray microscope for the water window2013In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 463, no 1, p. 012013-Article in journal (Refereed)
    Abstract [en]

    In the water window (2.2-4.4 nm) the attenuation of radiation in water is significantly smaller than in organic material. Therefore, intact biological specimen (e.g. cells) can be investigated in their natural environment. In order to make this technique accessible to users in a laboratory environment a Full-Field Laboratory Transmission X-ray Microscope (L-TXM) has been developed. The L-TXM is operated with a nitrogen laser plasma source employing an InnoSlab high power laser system for plasma generation. For microscopy the Ly α emission of highly ionized nitrogen at 2.48 nm is used. A laser plasma brightness of 5 × 1011 photons/(s × sr × μm2 in line at 2.48 nm) at a laser power of 70 W is demonstrated. In combination with a state-of-the-art Cr/V multilayer condenser mirror the sample is illuminated with 106 photons/(μm2 × s). Using objective zone plates 35-40 nm lines can be resolved with exposure times < 60 s. The exposure time can be further reduced to 20 s by the use of new multilayer condenser optics and operating the laser at its full power of 130 W. These exposure times enable cryo tomography in a laboratory environment.

  • 79. Lemor, Robert
    et al.
    Günther, Christian
    Fuhr, Günther
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Metod och anordning för akustisk manipulering av partiklar, celler och virus2005Patent (Other (popular science, discussion, etc.))
  • 80.
    Lindblom, Magnus
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Holmberg, Anders
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Pulse reverse electroplating for uniform nickel height in zone plates2006In: Journal of Vacuum Science & Technology B, ISSN 1071-1023, E-ISSN 1520-8567, Vol. 24, p. 2848-Article in journal (Refereed)
    Abstract [en]

    Nickelsoft x-ray zone plates are fabricated by through-mask electroplating. Theauthors report on how a uniform nickel thickness can beobtained over the entire zone plate using pulse and pulsereverse plating. If the plating is carried out at aconstant current the nickel thickness has been observed to decreasewith radius. This results in lower outer zones and reduceddiffraction efficiency in the outer parts of the zone plates.Here they show that the height profile can be controlledby adjusting the current density of the pulses. A highcurrent density is found to primarily affect the edges whilea low current density was observed to affect the centralparts of the structures. This is true for both cathodicand anodic currents, which means that local plating and dissolutionrates can be adjusted to obtain a uniform mass distribution.

  • 81.
    Lindblom, Magnus
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Holmberg, Anders
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    SU8 plating mold for high aspect-ratio nickel zone plates2007In: Microelectronic Engineering, ISSN 0167-9317, E-ISSN 1873-5568, Vol. 84, p. 1136-Article in journal (Refereed)
    Abstract [en]

    Nickel zone plates are fabricated by electrodeposition into a mold with high aspect ratio and narrow line width. This process requires high-mechanical stability of the mold to avoid pattern collapse in the plating bath. In the present paper we demonstrate how SU-8 can be used as plating mold material in a tri-layer resist to fabricate 35-nm half-pitch nickel gratings with an aspect ratio exceeding 11:1. To attain sufficient stability of the mold the SU-8 was cured by e-beam exposure with a dose of 25 mC/cm2 at 5-keV electron energy.

  • 82.
    Lindblom, Magnus
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Reinspach, Julia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Bertilson, Michael
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    von Hofsten, Olov
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Holmberg, Anders
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Nickel-germanium soft x-ray zone plates2009In: Journal of Vacuum Science & Technology B, ISSN 1071-1023, E-ISSN 1520-8567, Vol. 27, no 3, p. L5-L7Article in journal (Refereed)
    Abstract [en]

    This article presents a fabrication process for soft x-ray zone plates in which nickel and germanium are combined to achieve high diffraction efficiency. A nickel zone plate is first fabricated on a germanium film and then used as a hardmask for a CHF3-plasma etch into the germanium. Zone plates with 50-60 nm nickel and 110-150 nm of germanium are presented. The measured diffraction efficiencies were 10%-11% at lambda=2.88 nm, which shows that high efficiency is possible even with thin nickel. Thus, the method has a potential for improving the efficiency of high-resolution zone plates for which the high-aspect-ratio structuring of nickel is difficult.

  • 83.
    Lindblom, Magnus
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Reinspach, Julia
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    von Hofsten, Olov
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Bertilson, Michael
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Holmberg, Anders
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    High-aspect-ratio germanium zone plates fabricated by ractive ion etching in chlorine2009In: Journal of Vacuum Science & Technology B, ISSN 1071-1023, E-ISSN 1520-8567, Vol. 27, no 2, p. L1-L3Article in journal (Refereed)
    Abstract [en]

    This article describes the fabrication of soft x-ray germanium zone plates with a process based on reactive ion etching (RIE) in Cl-2. A high degree of anisotropy is achieved by sidewall passivation through cyclic exposure to air. This enables structuring of higher aspect ratios than with earlier reported fabrication processes for germanium zone plates. The results include a zone plate with a 30 nm outermost zone width and a germanium thickness of 310 tun having a first-order diffraction efficiency of 70% of the theoretical value. 25 nm half-pitch gratings were also etched into 310 nut of germanium. Compared to the electroplating process for the commonly used nickel zone plates, the RIE process with Cl-2, for germanium is a major improvement in terms of process reproducibility.

  • 84.
    Lindblom, Magnus
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Tuohimaa, Tomi
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Holmberg, Anders
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Wilhein, Thomas
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Ulrich
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    High-resolution differential-interference-contrast x-ray zone plates: Design and Fabrication2007In: Spectrochimica Acta Part B - Atomic Spectroscopy, ISSN 0584-8547, E-ISSN 1873-3565, Vol. 62, no 6-7, p. 539-543Article in journal (Refereed)
    Abstract [en]

    Differential interference contrast is a potentially powerful technique for contrast enhancement in soft X-ray microscopy. We describe the design and fabrication of single-element diffractive optical elements suitable as objectives for high-resolution differential interference contrast microscopy in the water-window spectral range. A one-dimensional pattern calculation followed by an extension to two dimensions results in a pattern resolution of 1 nm, which is well below fabrication accuracy. The same fabrication process as for normal zone plates is applicable, but special care must be taken when converting the calculated pattern to a code for e-beam lithography.

  • 85.
    Lundström, Ulf
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Larsson, Daniel H.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Scott, L.
    Westermark, U. K.
    Wilhelm, M.
    Henriksson, M. Arsenian
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    X-ray phase-contrast CO2 angiography for sub-10 mu m vessel imaging2012In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 57, no 22, p. 7431-7441Article in journal (Refereed)
    Abstract [en]

    X-ray in-line phase contrast has recently been combined with CO2 angiography for high-resolution small-animal vascular imaging at low radiation dose. In this paper we further investigate the potential and limitations of this method and demonstrate observation of vessels down to 8 mu m in diameter, considerably smaller than the 60 mu m previously reported. Our in-line phase-contrast imaging system is based on a liquid-metal-jet-anode x-ray source and utilizes free-space propagation to convert phase shifts, caused by refractive index variations, into intensity differences. Enhanced refractive index variations are obtained through injection of CO2 gas into the vascular system to replace the blood. We show rat-kidney images with blood vessels down to 27 mu m in diameter and mouse-ear images with vessels down to 8 mu m. The minimum size of observable blood vessels is found to be limited by the penetration of gas into the vascular system and the signal-to-noise ratio, i.e. the allowed dose. The diameters of vessels being gas-filled depend on the gas pressure and follow a simple model based on surface tension. A theoretical signal-to-noise comparison shows that this method requires 1000 times less radiation dose than conventional iodine-based absorption contrast for observing sub-50 mu m vessels.

  • 86.
    Lundström, Ulf
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Larsson, Daniel H.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Takman, Per A. C.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Scott, L.
    Brismar, H.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    X-ray phase contrast for CO2 microangiography2012In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 57, no 9, p. 2603-2617Article in journal (Refereed)
    Abstract [en]

    We demonstrate a laboratory method for imaging small blood vessels using x-ray propagation-based phase-contrast imaging and carbon dioxide (CO2) gas as a contrast agent. The limited radiation dose in combination with CO2 being clinically acceptable makes the method promising for small-diameter vascular visualization. We investigate the possibilities and limitations of the method for small-animal angiography and compare it with conventional absorption-based x-ray angiography. Photon noise in absorption-contrast imaging prevents visualization of blood vessels narrower than 50 mu m at the highest radiation doses compatible with living animals, whereas our simulations and experiments indicate the possibility of visualizing 20 mu m vessels at radiation doses as low as 100 mGy. Experimental computed tomography of excised rat kidney shows blood vessels of diameters down to 60 mu m with improved image quality compared to absorption-based methods. With our present prototype x-ray source, the acquisition time for a tomographic dataset is approximately 1 h, which is long compared to the 1-20 min common for absorption-contrast micro-CT systems. Further development of the liquid-metal-jet microfocus x-ray sources used here and high-resolution x-ray detectors shows promise to reduce exposure times and make this high-resolution method practical for imaging of living animals.

  • 87.
    Lundström, Ulf
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Larsson, Daniel H.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Takman, Per
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Scott, L.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    X-ray phase contrast angiography using CO 2 as contrast agent2012In: Progress in Biomedical Optics and Imaging - Proceedings of SPIE, SPIE - International Society for Optical Engineering, 2012, Vol. 8313, p. 83135J-Conference paper (Refereed)
    Abstract [en]

    We investigate the possibility of using x-ray in-line phase-contrast imaging with gaseous carbon dioxide as contrast agent to visualize small blood vessels. These are difficult to image at reasonable radiation doses using the absorption of conventional iodinated contrast agents. In-line phase contrast is a method for retrieving information on the electron density of the sample as well as the absorption, by moving the detector away from the sample to let phase variations in the transmitted x-rays develop into intensity variations at the detector. Blood vessels are normally difficult to observe in phase contrast even with iodinated contrast agents as the density difference compared to most tissues is small. Carbon dioxide is a clinically accepted x-ray contrast agent. The gas is injected into the blood stream of patients to temporarily displace the blood in a region and thereby reduce the x-ray absorption in the blood vessels. This gives a large density difference which is ideal for phase-contrast imaging. We demonstrate the possibilities of the method by imaging the arterial system of a rat kidney injected with carbon dioxide. Vessels down to 23 ÎŒm in diameter are shown. The method shows potential for live small-animal imaging.

  • 88.
    Lundström, Ulf
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Larsson, Daniel H.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Westermark, U. K.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Small-Animal microangiography using phase-contrast X-ray imaging and gas as contrast agent2014In: Medical Imaging 2014: Physics of Medical Imaging, SPIE - International Society for Optical Engineering, 2014, p. 90331L-Conference paper (Refereed)
    Abstract [en]

    We use propagation-based phase-contrast X-ray imaging with gas as contrast agent To visualize The microvasculature in small animals like mice and rats. The radiation dose required for absorption X-ray imaging is proportional To The minus fourth power of The structure size To be detected. This makes small vessels impossible To image at reasonable radiation doses using The absorption of conventional iodinated contrast agents. Propagation-based phase contrast gives enhanced contrast for high spatial frequencies by moving The detector away from The sample To let phase variations in The Transmitted X-rays develop into intensity variations at The detector. Blood vessels are normally difficult To observe in phase contrast even with iodinated contrast agents as The density difference between blood and most Tissues is relatively small. By injecting gas into The blood stream This density difference can be greatly enhanced giving strong phase contrast. One possible gas To use is carbon dioxide, which is a clinically accepted X-ray contrast agent. The gas is injected into The blood stream of patients To Temporarily displace The blood in a region and Thereby reduce The X-ray absorption in The blood vessels. We have shown That This method can be used To image blood vessels down To 8 μm in diameter in mouse ears. The low dose requirements of This method indicate a potential for live small-Animal imaging and longitudinal studies of angiogenesis.

  • 89.
    Lundström, Ulf
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Westermark, Ulrica K.
    Larsson, Daniel H.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Arsenian Henriksson, Marie
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    X-ray phase contrast with injected gas for tumor microangiography2014In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 59, no 11, p. 2801-2811Article in journal (Refereed)
    Abstract [en]

    We show that the microvasculature of mouse tumors can be visualized using propagation-based phase-contrast x-ray imaging with gas as the contrast agent. The large density difference over the gas-tissue interface provides high contrast, allowing the imaging of small-diameter blood vessels with relatively short exposure times and low dose using a compact liquid-metal-jet x-ray source. The method investigated is applied to tumors (E1A/Ras-transformed mouse embryonic fibroblasts) grown in mouse ears, demonstrating sub-15-mu m-diameter imaging of their blood vessels. The exposure time for a 2D projection image is a few seconds and a full tomographic 3D map takes some minutes. The method relies on the strength of the vasculature to withstand the gas pressure. Given that tumor vessels are known to be more fragile than normal vessels, we investigate the tolerance of the vasculature of 12 tumors to gas injection and find that a majority withstand 200 mbar pressures, enough to fill 12-mu m-diameter vessels with gas. A comparison of the elasticity of tumorous and non-tumorous vessels supports the assumption of tumor vessels being more fragile. Finally, we conclude that the method has the potential to be extended to the imaging of 15 mu m vessels in thick tissue, including mouse imaging, making it of interest for, e.g., angiogenesis research.

  • 90.
    Manneberg, Otto
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Hagsäter, S. Melker
    Svennebring, Jessica
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Kutter, Jörg P.
    Bruus, Henrik
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Spatial confinement of ultrasonic force fields in microfluidic chips2009In: Ultrasonics, ISSN 0041-624X, E-ISSN 1874-9968, Vol. 49, p. 112-119Article in journal (Refereed)
    Abstract [en]

    We demonstrate and investigate multiple localized ultrasonic manipulation functions in series in microfluidic chips. The manipulation functions are based on spatially separated and confined ultrasonic primary radiation force fields, obtained by local matching of the resonance condition of the microfluidic channel. The channel segments are remotely actuated by the use of frequency-specific external transducers with refracting wedges placed on top of the chips. The force field in each channel segment is characterized by the use of micrometer-resolution particle image velocimetry ( micro-PIV). The confinement of the ultrasonic fields during single-or dual-segment actuation, as well as the cross-talk between two adjacent. fields, is characterized and quantified. Our results show that the field confinement typically scales with the acoustic wavelength, and that the cross-talk is insignificant between adjacent. fields. The goal is to define design strategies for implementing several spatially separated ultrasonic manipulation functions in series for use in advanced particle or cell handling and processing applications. One such proof-of-concept application is demonstrated, where. flow-through-mode operation of a chip with. flow splitting elements is used for two-dimensional pre-alignment and addressable merging of particle tracks.

  • 91.
    Manneberg, Otto
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hultström, Jessica
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Dynamics of ultrasonic standing wave nodal patterns in a microfluidic chip by acoustic streaming and coupling effects2007In: Proc. 1st International Congress on Ultrasonics, 2007Conference paper (Refereed)
  • 92.
    Manneberg, Otto
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hultström, Jessica
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Elementary manipulation functions for gentle and long-term handling of cells in micro-channels by ultrasonic standing waves2006In: Proc. 10th Annual European Conference on Micro & Nanoscale Technologies for the Biosciences, 2006Conference paper (Refereed)
  • 93.
    Manneberg, Otto
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hultström, Jessica
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Proliferation of adherent cells manipulated by standing wave ultrasound in a microfluidic chip2006Conference paper (Other academic)
  • 94.
    Manneberg, Otto
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Svennebring, Jessica
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Towards spatially confined ultrasonic standing wave fields in a microfluidic chip by microchannel design2007Conference paper (Refereed)
  • 95.
    Manneberg, Otto
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Svennebring, Jessica
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Ultrasonic micro-cages: A new approach for manipulation and monitoring of individual cells and for fluid mixing2008In: 12th International Conference on Miniaturized Systems for Chemistry and Life Sciences - The Proceedings of MicroTAS 2008 Conference, Chemical and Biological Microsystems Society , 2008, p. 1495-1497Conference paper (Refereed)
    Abstract [en]

    Four designs of ultrasonic microcages are presented together with force field simulations and experimental verification. The microcages enable three-dimensional ultrasonic manipulation of individual microparticles combined with on-line monitoring using high-resolution optical microscopy. The microcages can also be employed as acoustic-streaming-based micromixers. We investigate and compare the force field distributions and streaming patterns in the cages, and we demonstrate concentration, aggregation and positioning of individual particles. The cages can be used for, e.g., studies of interactions between single cells and functionalized particles or pairs of cells in contact only with each other.

  • 96.
    Manneberg, Otto
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Svennebring, Jessica
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Wedge transducer design for two-dimensional ultrasonic manipulation in a microfluidic chip2008In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 18, p. 095025-Article in journal (Refereed)
    Abstract [en]

    We analyze and optimize the design of wedge transducers used for the excitation of resonances in the channel of a microfluidic chip in order to efficiently manipulate particles or cells in more than one dimension. The design procedure is based on (1) theoretical modeling of acoustic resonances in the transducer-chip system and calculation of the force fields in the fluid channel, (2) full-system resonance characterization by impedance spectroscopy and (3) image analysis of the particle distribution after ultrasonic manipulation. We optimize the transducer design in terms of actuation frequency, wedge angle and placement on top of the chip, and we characterize and compare the coupling effects in orthogonal directions between single- and dual-frequency ultrasonic actuation. The design results are verified by demonstrating arraying and alignment of particles in two dimensions. Since the device is compatible with high-resolution optical microscopy, the target application is dynamic cell characterization combined with improved microfluidic sample transport.

  • 97.
    Manneberg, Otto
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vanherberghen, Bruno
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Svennebring, Jessica
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Önfelt, Björn
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    A three-dimensional ultrasonic cage for characterization of individual cells2008In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 93, p. 063901-Article in journal (Refereed)
    Abstract [en]

    We demonstrate enrichment, controlled aggregation, and manipulation of microparticles and cells by an ultrasonic cage integrated in a microfluidic chip compatible with high-resolution optical microscopy. The cage is designed as a dual-frequency resonant filleted square box integrated in the fluid channel. Individual particles may be trapped three dimensionally, and the dimensionality of one-dimensional to three-dimensional aggregates can be controlled. We investigate the dependence of the shape and position of a microparticle aggregate on the actuation voltages and aggregate size, and demonstrate optical monitoring of individually trapped live cells with submicrometer resolution.

  • 98.
    Manneberg, Otto
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vanherberghen, Bruno
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Svennebring, Jessica
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Önfelt, Björn
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Ultrasonic microcages for high-resolution characterization of individual cells2008Conference paper (Refereed)
  • 99.
    Martz, Dale H.
    et al.
    KTH.
    Selin, Mårten
    KTH.
    von Hofsten, Olov
    KTH.
    Fogelqvist, Emelie
    KTH.
    Holmberg, Anders
    KTH.
    Vogt, Ulrich
    KTH.
    Legall, H.
    Max-Born-Institute, Germany .
    Blobel, G.
    Max-Born-Institute, Germany .
    Seim, C.
    nstitute of Optics and Atomic Physics—Analytical X-ray physics, Germany .
    Stiel, H.
    Max-Born-Institute, Germany .
    Hertz, Hans M.
    KTH.
    High average brightness water window source for short-exposure cryomicroscopy2012In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 37, no 21, p. 4425-4427Article in journal (Refereed)
    Abstract [en]

    Laboratory water window cryomicroscopy has recently demonstrated similar image quality as synchrotron-based microscopy but still with much longer exposure times, prohibiting the spread to a wider scientific community. Here we demonstrate high-resolution laboratory water window imaging of cryofrozen cells with 10 s range exposure times. The major improvement is the operation of a lambda = 2.48 nm, 2 kHz liquid nitrogen jet laser plasma source with high spatial and temporal stability at high average brightness >1.5 x 10(12) ph/(s x sr x mu m(2) x line), i.e., close to that of early synchrotrons. Thus, this source enables not only biological x-ray microscopy in the home laboratory but potentially other applications previously only accessible at synchrotron facilities.

  • 100.
    Martz, Dale H.
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Selin, Mårten
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    von Hofsten, Olov
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Fogelqvist, Emelie
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Holmberg, Anders
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Ulrich
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Legall, H.
    Blobel, G.
    Seim, C.
    Stiel, H.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    High average brightness water window source for short-exposure cryomicroscopy2012In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 37, no 21, p. 4425-4427Article in journal (Refereed)
    Abstract [en]

    Laboratory water window cryomicroscopy has recently demonstrated similar image quality as synchrotron-based microscopy but still with much longer exposure times, prohibiting the spread to a wider scientific community. Here we demonstrate high-resolution laboratory water window imaging of cryofrozen cells with 10 s range exposure times. The major improvement is the operation of a lambda = 2.48 nm, 2 kHz liquid nitrogen jet laser plasma source with high spatial and temporal stability at high average brightness >1.5 x 10(12) ph/(s x sr x mu m(2) x line), i.e., close to that of early synchrotrons. Thus, this source enables not only biological x-ray microscopy in the home laboratory but potentially other applications previously only accessible at synchrotron facilities.

1234 51 - 100 of 175
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