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  • 1. Farahi, R. H.
    et al.
    Passian, A.
    Zahrai, Said
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Lereu, A. L.
    Ferrell, T. L.
    Thundat, T.
    Microscale Marangoni actuation: All-optical and all-electrical methods2006In: Ultramicroscopy, ISSN 0304-3991, E-ISSN 1879-2723, Vol. 106, no 8-9, p. 815-821Article in journal (Refereed)
    Abstract [en]

    We present experimental results from an all-optical microfluidic platform that may be complimented by a thin film all-electrical network. Using these configurations we have studied the microfluidic convective flow systems of silicone oil, glycerol, and 1,3,5-trinitrotoluene on open surfaces through the production of surface tension gradients derived from thermal gradients. We show that sufficient localized thermal variation can be created utilizing surface plasmons and/or engaging individually addressable resistive thermal elements. Both studies manipulate fluids via Marangoni forces, each having their unique exploitable advantages. Surface plasmon excitation in metal foils are the driving engine of many physical-, chemical-, and bio-sensing applications. Incorporating, for the first time, the plasmon concept in microfluidics, our results thus demonstrate great potential for simultaneous fluid actuation and sensing. (c) 2006 Elsevier B.V. All rights reserved.

  • 2.
    Koeck, Philip J. B.
    KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Structural Biotechnology. Karolinska Institutet, Sweden.
    Improved Hilbert phase contrast for transmission electron microscopy2015In: Ultramicroscopy, ISSN 0304-3991, E-ISSN 1879-2723, Vol. 154, p. 37-41Article in journal (Refereed)
    Abstract [en]

    Hilbert phase contrast has been recognized as a means of recording high resolution images with high contrast using a transmission electron microscope. This imaging mode could be used to image typical phase objects such as unstained biological molecules or cryo sections of biological tissue. According to the original proposal by (Danev et al., 2002) the Hilbert phase plate applies a phase shift of π to approximately half the focal plane (for example the right half excluding the central beam) and an image is recorded at Gaussian focus. After correction for the inbuilt asymmetry of differential phase contrast this image will have an almost perfect contrast transfer function (close to 1) from the lowest spatial frequency up to a maximum resolution determined by the wave length and spherical aberration of the microscope. In this paper I present theory and simulations showing that this maximum spatial frequency can be increased considerably almost without loss of contrast by using a Hilbert phase plate of half the thickness, leading to a phase shift of π/2, and recording images at Scherzer defocus. The maximum resolution can be improved even more by imaging at extended Scherzer defocus, though at the cost of contrast loss at lower spatial frequencies.

  • 3.
    Koeck, Philip J. B.
    KTH, School of Technology and Health (STH), Medical Engineering, Structural Biotechnology. Karolinska Institutet, Department of Biosciences and Nutrition, Novum, 14183 Huddinge, Sweden.
    An aperture design for single side band imaging in the transmission electron microscope2017In: Ultramicroscopy, ISSN 0304-3991, E-ISSN 1879-2723, Vol. 182, p. 81-84Article in journal (Refereed)
  • 4.
    Koeck, Philip J. B.
    KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Structural Biotechnology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Structural Biotechnology. Department of Biosciences and Nutrition, Novum, Huddinge, Sweden.
    Annular dark field transmission electron microscopy for protein structure determination2016In: Ultramicroscopy, ISSN 0304-3991, E-ISSN 1879-2723, Vol. 161, p. 98-104Article in journal (Refereed)
    Abstract [en]

    Recently annular dark field (ADF) transmission electron microscopy (TEM) has been advocated as a means of recording images of biological specimens with better signal to noise ratio (SNR) than regular bright field images. I investigate whether and how such images could be used to determine the three-dimensional structure of proteins given that an ADF aperture with a suitable pass-band can be manufactured and used in practice. I develop an approximate theory of ADF-TEM image formation for weak amplitude and phase objects and test this theory using computer simulations. I also test whether these simulated images can be used to calculate a three-dimensional model of the protein using standard software and discuss problems and possible ways to overcome these.

  • 5.
    Koeck, Philip J. B.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Structural Biotechnology. Karolinska Institutet, Department of Biosciences and Nutrition, Huddinge, Sweden.
    Design of a Charged Particle Beam Phase Plate for Transmission Electron Microscopy2019In: Ultramicroscopy, ISSN 0304-3991, E-ISSN 1879-2723, Vol. 205, p. 62-69Article in journal (Refereed)
  • 6. Koelling, S.
    et al.
    Innocenti, Nicolas
    KTH, School of Computer Science and Communication (CSC), Computational Biology, CB.
    Bogdanowicz, J.
    Vandervorst, W.
    Optimal laser positioning for laser-assisted atom probe tomography2013In: Ultramicroscopy, ISSN 0304-3991, E-ISSN 1879-2723, Vol. 132, p. 70-74Article in journal (Refereed)
    Abstract [en]

    Laser-assisted atom probe tomography is a material analysis method based on field evaporating ions from a tip-shaped sample by a combination of a standing electric held and a short (pico- or lemtosecond) laser pulse. The laser-pulse thereby acts as a starting signal for a time-of-flight mass analysis of the ions whereby the thermal energy deposited in the tip by the laser pulse temporarily enables the evaporation of ions from the surface of the tip. Here we will use simulations of the laser absorption on a silicon tip to find the optimal position of the laser spot in order to maximize the mass resolution achieved during the experiments. We will confirm our simulations by showing that the experimentally observed mass resolution indeed changes as predicted by the simulations.

  • 7.
    Koelling, Sebastian
    et al.
    Imec, Kapeldreef 75, B-3000 Leuven, Belgium.
    Innocenti, Nicolas
    Imec, Kapeldreef 75, B-3000 Leuven, Belgium; University of Liege, Institut Montefiore .
    Hellings, Geert Hellings
    Imec, Kapeldreef 75, B-3000 Leuven, Belgium.
    Gilbert, Matthieu
    Imec, Kapeldreef 75, B-3000 Leuven, Belgium.
    Kambham, Ajay Kumar
    Imec, Kapeldreef 75, B-3000 Leuven, Belgium.
    De Meyer, Kristin
    Imec, Kapeldreef 75, B-3000 Leuven, Belgium.
    Vandervorst, Wilfried
    Imec, Kapeldreef 75, B-3000 Leuven, Belgium.
    Characteristics of cross-sectional atom probe analysis on semiconductor structures2011In: Ultramicroscopy, ISSN 0304-3991, E-ISSN 1879-2723, Vol. 111, no 6, p. 540-545Article in journal (Refereed)
    Abstract [en]

    The laser-assisted Atom Probe has been proposed as a metrology tool for next generation semiconductor technologies requiring sub-nm spatial resolution. In order to assess its potential for the analysis of three-dimensional semiconductor structures like FinFETs, we have studied the Atom Probes lateral resolution on a silicon, silicon–germanium multilayer structure. We find that the interactions of the laser with the semiconductor materials in the sample distort the sample surface. This results in transient errors of the measured dimensions of the structure. The deformation of the sample furthermore leads to a degradation of the lateral resolution. In the experiments presented in this paper, the Atom Probe reaches a lateral resolution of 1-1.8 nm/decade. In this paper we will discuss the reasons for the distortions of the tip and demonstrate that with the present state of data reconstruction severe quantification errors limit its applicability for the quantitative analysis of heterogeneous semiconductor structures. Our experiments show that reconstruction algorithms taking into account the time dependent nanostructure of the tip shape are required to arrive at accurate results.

  • 8.
    Köck, Philip J. B.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Structural Biotechnology. Karolinska Institutet, Department of Biosciences and Nutrition, Novum, Huddinge, Sweden.
    Design of an Electrostatic Phase Shifting Device for Biological Transmission Electron Microscopy2018In: Ultramicroscopy, ISSN 0304-3991, E-ISSN 1879-2723, Vol. 187, p. 107-112Article in journal (Refereed)
    Abstract [en]

    I suggest an electrostatic phase plate designed to broaden the contrast transfer function of a transmission electron microscope operated close to Scherzer defocus primarily in the low resolution direction. At higher defocus the low frequency behavior is equal to that close to Scherzer defocus, but CTF-correction becomes necessary to extend image interpretation to higher resolution. One simple realization of the phase plate consists of two ring shaped electrodes symmetrically surrounding the central beam. Since no physical components come into contact with the central beam and charge on the electrodes is controlled by an external voltage supply, problems with uncontrolled charging are expected to be reduced.

  • 9.
    Platz, Daniel
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Tholén, Erik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Hutter, Carsten
    von Bieren, Arndt
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Haviland, David
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Phase imaging with intermodulation atomic force microscopy2010In: Ultramicroscopy, ISSN 0304-3991, E-ISSN 1879-2723, Vol. 110, no 6, p. 573-577Article in journal (Refereed)
    Abstract [en]

    Intermodulation atomic force microscopy (IMAFM) is a dynamic mode of atomic force microscopy (AFM) with two-tone excitation. The oscillating AFM cantilever in close proximity to a surface experiences the nonlinear tip-sample force which mixes the drive tones and generates new frequency components in the cantilever response known as intermodulation products (IMPs). We present a procedure for extracting the phase at each IMP and demonstrate phase images made by recording this phase while scanning. Amplitude and phase images at intermodulation frequencies exhibit enhanced topographic and material contrast.

  • 10.
    Shen, Rickard Ruici
    et al.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.).
    Efsing, Pål
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.).
    Overcoming the drawbacks of plastic strain estimation based on KAM2018In: Ultramicroscopy, ISSN 0304-3991, E-ISSN 1879-2723, Vol. 184, p. 156-163Article in journal (Refereed)
    Abstract [en]

    Plastic strain estimation using electron backscatter diffraction (EBSD) based on kernel average misorientation (KAM) is affected by random orientation measurement error, EBSD step length, choice of kernel and average grain size. These sensitivities complicate reproducibility of results between labs, but it is shown in this work how these drawbacks can be overcome. The modifications to KAM were verified against a similar misorientation metric based on grain orientation spread (GOS), which does not show sensitivity to these factors. Both metrics were used in parallel to estimate the plastic strain distribution in Alloy 690 heat affected zones from component mockups, and showed the same results where the grain size was correctly compensated for.

  • 11.
    Stoltz, Dunja
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Önsten, Anneli
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Karlsson, Ulf O.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Göthelid, Mats
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Scanning tunneling microscopy of Fe- and O-sublattices on Fe3O4(100)2008In: Ultramicroscopy, ISSN 0304-3991, E-ISSN 1879-2723, Vol. 108, no 6, p. 540-544Article in journal (Refereed)
    Abstract [en]

    We present scanning tunneling microscopy of an octahedral (B) plane terminated (root 2 x root 2)R45 degrees-reconstructed surface of a natural magnetite (10 0) crystal. Implementing a W-tip we achieve the same resolution on Fe rows as was reported in the past either with the use of antiferromagnetic tips or on magnetite (Fe3O4) films. We show images of Fe or O sublattices of Fe3O4 with atomic resolution.

  • 12.
    Thormann, Esben
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pettersson, Torbjörn
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Kettle, John
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Probing material properties of polymeric surface layers with tapping mode AFM: Which cantilever spring constant, tapping amplitude and amplitude set point gives good image contrast and minimal surface damage?2010In: Ultramicroscopy, ISSN 0304-3991, E-ISSN 1879-2723, Vol. 110, no 4, p. 313-319Article in journal (Refereed)
    Abstract [en]

    A phase shift between the oscillatory motion and drive motion of an AFM-cantilever used for tapping mode AFM imaging can be related to adhesive and elastic properties of surface layers. In this study it was studied how optimal contrast between hard and soft surface layers can be achieved while minimizing the surface damage. This was investigated by performing classical force-distance measurements while driving the cantilever as in tapping mode imaging. The amplitude and phase response as a function of the average tip-surface separation was recorded. Five different cantilevers with a wide range of spring constants and four different tapping amplitudes were investigated and compared. Based on these experiments it is concluded that too stiff cantilever, high free tapping amplitude and low amplitude set point value often lead to surface damage, while too low spring constant and low free tapping amplitude result in poor phase image contrast. Intermediate values where little surface damage and significant image contrast are obtained were identified. In all cases it was observed that the best image contrast was obtained when the amplitude set point was chosen such that the amplitude during imaging was reduced to approximately 50% of the free amplitude.

  • 13.
    von Hofsten, Olov
    et al.
    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.
    Voght, Ulrich
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Simulation of partially coherent image formation in a compact soft x-ray microscope2007In: Ultramicroscopy, ISSN 0304-3991, E-ISSN 1879-2723, Vol. 107, no 8, p. 604-609Article in journal (Refereed)
    Abstract [en]

    In this paper, we describe a numerical method of simulating two-dimensional images in a compact soft X-ray microscope using partially coherent illumination considerations. The work was motivated by recent test object images obtained by the latest generation inhouse compact soft X-ray microscope, which showed diffraction-like artifacts not observed previously. The numerical model approximates the condenser zone plate as a secondary incoherent source represented by individually coherent but mutually incoherent source points, each giving rise to a separate image. A final image is obtained by adding up all the individual source point contributions. The results are compared with the microscope images and show qualitative agreement, indicating that the observed effects are caused by partially coherent illumination.

  • 14. Zhong, Z.
    et al.
    Palenstijn, W. J.
    Adler, Jonas
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematics (Div.). Elekta, Stockholm, Sweden.
    Batenburg, K. J.
    EDS tomographic reconstruction regularized by total nuclear variation joined with HAADF-STEM tomography2018In: Ultramicroscopy, ISSN 0304-3991, E-ISSN 1879-2723, Vol. 191, p. 34-43Article in journal (Refereed)
    Abstract [en]

    Energy-dispersive X-ray spectroscopy (EDS) tomography is an advanced technique to characterize compositional information for nanostructures in three dimensions (3D). However, the application is hindered by the poor image quality caused by the low signal-to-noise ratios and the limited number of tilts, which are fundamentally limited by the insufficient number of X-ray counts. In this paper, we explore how to make accurate EDS reconstructions from such data. We propose to augment EDS tomography by joining with it a more accurate high-angle annular dark-field STEM (HAADF-STEM) tomographic reconstruction, for which usually a larger number of tilt images are feasible. This augmentation is realized through total nuclear variation (TNV) regularization, which encourages the joint EDS and HAADF reconstructions to have not only sparse gradients but also common edges and parallel (or antiparallel) gradients. Our experiments show that reconstruction images are more accurate compared to the non-regularized and the total variation regularized reconstructions, even when the number of tilts is small or the X-ray counts are low.

  • 15. Zou, X D
    et al.
    Hovmöller, Anders
    KTH.
    Hovmoller, S
    TRICE - A program for reconstructing 3D reciprocal space and determining unit-cell parameters2004In: Ultramicroscopy, ISSN 0304-3991, E-ISSN 1879-2723, Vol. 98, no 2-4, p. 187-193Article in journal (Refereed)
    Abstract [en]

    A program system-Trice-for reconstructing the 3D reciprocal lattice from an electron diffraction tilt series is described. The unit-cell parameters can be determined from electron diffraction patterns directly by Trice. The unit cell can be checked and the lattice type and crystal system can be determined from the 3D reciprocal lattice. Trice can be applied to all crystal systems and lattice types.

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