C. Kisielowski - Academia.edu (original) (raw)
Papers by C. Kisielowski
Science (New York, N.Y.), Jan 8, 2011
The study of first-order structural transformations has been of great interest to scientists in m... more The study of first-order structural transformations has been of great interest to scientists in many disciplines. Expectations from phase-transition theory are that the system fluctuates between two equilibrium structures near the transition point and that the region of transition broadens in small crystals. We report the direct observation of structural fluctuations within a single nanocrystal using transmission electron microscopy. We observed trajectories of structural transformations in individual nanocrystals with atomic resolution, which reveal details of the fluctuation dynamics, including nucleation, phase propagation, and pinning of structural domains by defects. Such observations provide crucial insight for the understanding of microscopic pathways of phase transitions.
![Research paper thumbnail of Quantification of the Resolved Phase Change in Reconstructed Electron Exit Waves of Gold [110] in Different Electron Microscopes](https://attachments.academia-assets.com/98475638/thumbnails/1.jpg)
](Microscopy and Microanalysis, 2002
Micron (Oxford, England : 1993), 2015
This paper describes an approach to retrieve the three-dimensional atomic structure of a nanocrys... more This paper describes an approach to retrieve the three-dimensional atomic structure of a nanocrystalline particle from the reconstructed electron exit wave function in a single projection direction. The method employs wave propagation to determine the local exit surface of each atomic column together with its mass. The exit wave in between colums is used as internal calibration so as to remove the background noise and improve the precision to the level of single atom sensitivity. The validity of the approach is tested with exit wave functions of a gold wedge reconstructed from simulated images containing different levels of noise.
EMC 2008 14th European Microscopy Congress 1–5 September 2008, Aachen, Germany
The Transmission Electron Aberration-corrected Microscope (TEAM) project was initiated by the US ... more The Transmission Electron Aberration-corrected Microscope (TEAM) project was initiated by the US Department of Energy as a collaborative effort to redesign the electron microscope around aberration-corrected optics [1], and is aimed at achieving 50 pm resolution. But the ability to resolve deep sub-Ångstrom spacing entails a number of unresolved questions that can now be addressed. Among them is an ongoing debate about the physical meaning of resolution. Traditional strategies include the recording of Young’s fringes, the detection of image Fourier components from STEM images, the demonstration of a suitable peak separation in periodic lattices or signal width measurements from images of single atoms, to name a few. The drawback is that seemingly conflicting results are produced [e.g. 2]. Further, these methods define resolution through a selectable object, unlike light microscopy where resolution is instrument-defined. Two limitations of this approach are electron channeling [3, 4] and elastic scattering at single crystals [5]. The TEAM Project adopted a pragmatic view of information transfer below 50 pm: detecting Young’s fringes in TEM and (660) image Fourier components from gold (111) STEM images at 48 pm. Recently the TEAM 0.5 prototype microscope achieved this goal [1].
MRS Proceedings, 2004
ABSTRACTNovel Fe2O3 nanowires have been successfully synthesized by a simple oxidation process of... more ABSTRACTNovel Fe2O3 nanowires have been successfully synthesized by a simple oxidation process of pure iron. The microstructure of the Fe2O3 nanowires have been systematically investigated by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM). The investigated materials are found to be stoichiometric rhombohedral α-Fe2O3 with typical diameters of 20–80 nm and lengths up to 20 μm. In addition to known single crystal Fe2O3 nanowires, a great amount of novel bicrystalline nanowires were found with ellipsoidal heads. Investigations indicate that most of the bicrystalline nanowires are twins and their orientation relationship is obtained to be (−1, 1, 10)M//(−1, 1, 10)T, [110]M//[-1-10]T. High resolution TEM with numerical reconstruction of the electron exit wave was used to investigated the atomic structure of the micro-twins. Their growth mechanism is briefly discussed on the basis of solid phase growth process.
NATO Science Series II: Mathematics, Physics and Chemistry
This contribution reviews the current status of sub Ångstrom electron microscopy. High Resolution... more This contribution reviews the current status of sub Ångstrom electron microscopy. High Resolution Transmission Electron Microscopy (HRTEM) and Scanning Transmission Electron Microscopy (STEM) are considered and compared for imaging applications. While both techniques provide comparable sub Ångstrom resolution around 0.8Å noise levels and chemical discrimination are dissimilar, which result in complementary characteristics for the detection of different elements. In particular, the ability to detect single atoms benefits greatly from the ongoing resolution enhancement and corrections of lens aberrations. As a result it is feasible aiming at single atom analyses in three dimensions.
MRS Proceedings, 1997
ABSTRACTGaN films were grown on sapphire substrates at temperatures below 725 °C utilizing a Cons... more ABSTRACTGaN films were grown on sapphire substrates at temperatures below 725 °C utilizing a Constricted Glow Discharge plasma source. A three dimensional growth mode is observed at such low growth temperatures resulting in films that are composed of individual but oriented grains. The strain that originates from the growth on the lattice mismatched substrate with a different thermal expansion coefficient is utilized to influence the thin film growth. The strain can be largely altered by the growth of suitable buffer layers. Thereby, optical and structural film properties can be engineered. It is argued that the surface diffusion of Ga ad-atoms is affected by engineering the strain. Alternatively, surface diffusion can be influenced by surfactants. It is demonstrated that the use of bismuth as a surfactant allows to modify the surface morphology of the GaN films that reflects the size of the grains in the films. The results suggest that a substantial increase of the oriented grain s...
Angewandte Chemie (International ed. in English), Jan 26, 2014
The functional properties of transition metal dichalcogenides (TMDs) may be promoted by the inclu... more The functional properties of transition metal dichalcogenides (TMDs) may be promoted by the inclusion of other elements. Here, we studied the local stoichiometry of single cobalt promoter atoms in an industrial-style MoS2-based hydrotreating catalyst. Aberration-corrected scanning transmission electron microscopy and electron energy loss spectroscopy show that the Co atoms occupy sites at the (-100) S edge terminations of the graphite-supported MoS2 nanocrystals in the catalyst. Specifically, each Co atom has four neighboring S atoms that are arranged in a reconstructed geometry, which reflects an equilibrium state. The structure agrees with complementary studies of catalysts that were prepared under vastly different conditions and on other supports. In contrast, a small amount of residual Fe in the graphite is found to compete for the S edge sites, so that promotion by Co is strongly sensitive to the purity of the raw materials. The present single-atom-sensitive analytical method t...
Microsc …, 2005
The use of bright field TEM for tomography in physical sciences is often hampered by Bragg contri... more The use of bright field TEM for tomography in physical sciences is often hampered by Bragg contributions. In Figure 1 it is illustrated that the morphology of Pt nanoparticles (5-7 nm) is well reconstructed, but artificial cavities are observed inside the 3D reconstructions of the ...
MRS Proceedings, 2004
ABSTRACTIn this study we examine the immediate interface between matrix grains and the amorphous ... more ABSTRACTIn this study we examine the immediate interface between matrix grains and the amorphous intergranular film in a Si3N4 ceramic doped with rare-earth oxides La2O3, Sm2O3, Er2O3, Yb2O3 and Lu2O3, extracting unique structural and atomic bonding information. In particular, we relate the structure of the interface to the ionic size and electronic structure of the rare-earth elements and the presence of oxygen in the intergranular film. We relate these results to the measured fracture toughness.
Microscopy and Microanalysis, 2014
Science, 2009
Although the physics of materials at surfaces and edges has been extensively studied, the movemen... more Although the physics of materials at surfaces and edges has been extensively studied, the movement of individual atoms at an isolated edge has not been directly observed in real time. With a transmission electron aberration–corrected microscope capable of simultaneous atomic spatial resolution and 1-second temporal resolution, we produced movies of the dynamics of carbon atoms at the edge of a hole in a suspended, single atomic layer of graphene. The rearrangement of bonds and beam-induced ejection of carbon atoms are recorded as the hole grows. We investigated the mechanism of edge reconstruction and demonstrated the stability of the “zigzag” edge configuration. This study of an ideal low-dimensional interface, a hole in graphene, exhibits the complex behavior of atoms at a boundary.
Physical Review Letters, 2011
Physica B: Condensed Matter, 2006
Microscopy and Microanalysis, 2007
Extended abstract of a paper presented at Microscopy and Microanalysis 2007 in Ft. Lauderdale, Fl... more Extended abstract of a paper presented at Microscopy and Microanalysis 2007 in Ft. Lauderdale, Florida, USA, August 5 – August 9, 2007
Microscopy and Microanalysis, 2005
Microscopy and Microanalysis, 2005
Science (New York, N.Y.), Jan 8, 2011
The study of first-order structural transformations has been of great interest to scientists in m... more The study of first-order structural transformations has been of great interest to scientists in many disciplines. Expectations from phase-transition theory are that the system fluctuates between two equilibrium structures near the transition point and that the region of transition broadens in small crystals. We report the direct observation of structural fluctuations within a single nanocrystal using transmission electron microscopy. We observed trajectories of structural transformations in individual nanocrystals with atomic resolution, which reveal details of the fluctuation dynamics, including nucleation, phase propagation, and pinning of structural domains by defects. Such observations provide crucial insight for the understanding of microscopic pathways of phase transitions.
Microscopy and Microanalysis, 2002
Micron (Oxford, England : 1993), 2015
This paper describes an approach to retrieve the three-dimensional atomic structure of a nanocrys... more This paper describes an approach to retrieve the three-dimensional atomic structure of a nanocrystalline particle from the reconstructed electron exit wave function in a single projection direction. The method employs wave propagation to determine the local exit surface of each atomic column together with its mass. The exit wave in between colums is used as internal calibration so as to remove the background noise and improve the precision to the level of single atom sensitivity. The validity of the approach is tested with exit wave functions of a gold wedge reconstructed from simulated images containing different levels of noise.
EMC 2008 14th European Microscopy Congress 1–5 September 2008, Aachen, Germany
The Transmission Electron Aberration-corrected Microscope (TEAM) project was initiated by the US ... more The Transmission Electron Aberration-corrected Microscope (TEAM) project was initiated by the US Department of Energy as a collaborative effort to redesign the electron microscope around aberration-corrected optics [1], and is aimed at achieving 50 pm resolution. But the ability to resolve deep sub-Ångstrom spacing entails a number of unresolved questions that can now be addressed. Among them is an ongoing debate about the physical meaning of resolution. Traditional strategies include the recording of Young’s fringes, the detection of image Fourier components from STEM images, the demonstration of a suitable peak separation in periodic lattices or signal width measurements from images of single atoms, to name a few. The drawback is that seemingly conflicting results are produced [e.g. 2]. Further, these methods define resolution through a selectable object, unlike light microscopy where resolution is instrument-defined. Two limitations of this approach are electron channeling [3, 4] and elastic scattering at single crystals [5]. The TEAM Project adopted a pragmatic view of information transfer below 50 pm: detecting Young’s fringes in TEM and (660) image Fourier components from gold (111) STEM images at 48 pm. Recently the TEAM 0.5 prototype microscope achieved this goal [1].
MRS Proceedings, 2004
ABSTRACTNovel Fe2O3 nanowires have been successfully synthesized by a simple oxidation process of... more ABSTRACTNovel Fe2O3 nanowires have been successfully synthesized by a simple oxidation process of pure iron. The microstructure of the Fe2O3 nanowires have been systematically investigated by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM). The investigated materials are found to be stoichiometric rhombohedral α-Fe2O3 with typical diameters of 20–80 nm and lengths up to 20 μm. In addition to known single crystal Fe2O3 nanowires, a great amount of novel bicrystalline nanowires were found with ellipsoidal heads. Investigations indicate that most of the bicrystalline nanowires are twins and their orientation relationship is obtained to be (−1, 1, 10)M//(−1, 1, 10)T, [110]M//[-1-10]T. High resolution TEM with numerical reconstruction of the electron exit wave was used to investigated the atomic structure of the micro-twins. Their growth mechanism is briefly discussed on the basis of solid phase growth process.
NATO Science Series II: Mathematics, Physics and Chemistry
This contribution reviews the current status of sub Ångstrom electron microscopy. High Resolution... more This contribution reviews the current status of sub Ångstrom electron microscopy. High Resolution Transmission Electron Microscopy (HRTEM) and Scanning Transmission Electron Microscopy (STEM) are considered and compared for imaging applications. While both techniques provide comparable sub Ångstrom resolution around 0.8Å noise levels and chemical discrimination are dissimilar, which result in complementary characteristics for the detection of different elements. In particular, the ability to detect single atoms benefits greatly from the ongoing resolution enhancement and corrections of lens aberrations. As a result it is feasible aiming at single atom analyses in three dimensions.
MRS Proceedings, 1997
ABSTRACTGaN films were grown on sapphire substrates at temperatures below 725 °C utilizing a Cons... more ABSTRACTGaN films were grown on sapphire substrates at temperatures below 725 °C utilizing a Constricted Glow Discharge plasma source. A three dimensional growth mode is observed at such low growth temperatures resulting in films that are composed of individual but oriented grains. The strain that originates from the growth on the lattice mismatched substrate with a different thermal expansion coefficient is utilized to influence the thin film growth. The strain can be largely altered by the growth of suitable buffer layers. Thereby, optical and structural film properties can be engineered. It is argued that the surface diffusion of Ga ad-atoms is affected by engineering the strain. Alternatively, surface diffusion can be influenced by surfactants. It is demonstrated that the use of bismuth as a surfactant allows to modify the surface morphology of the GaN films that reflects the size of the grains in the films. The results suggest that a substantial increase of the oriented grain s...
Angewandte Chemie (International ed. in English), Jan 26, 2014
The functional properties of transition metal dichalcogenides (TMDs) may be promoted by the inclu... more The functional properties of transition metal dichalcogenides (TMDs) may be promoted by the inclusion of other elements. Here, we studied the local stoichiometry of single cobalt promoter atoms in an industrial-style MoS2-based hydrotreating catalyst. Aberration-corrected scanning transmission electron microscopy and electron energy loss spectroscopy show that the Co atoms occupy sites at the (-100) S edge terminations of the graphite-supported MoS2 nanocrystals in the catalyst. Specifically, each Co atom has four neighboring S atoms that are arranged in a reconstructed geometry, which reflects an equilibrium state. The structure agrees with complementary studies of catalysts that were prepared under vastly different conditions and on other supports. In contrast, a small amount of residual Fe in the graphite is found to compete for the S edge sites, so that promotion by Co is strongly sensitive to the purity of the raw materials. The present single-atom-sensitive analytical method t...
Microsc …, 2005
The use of bright field TEM for tomography in physical sciences is often hampered by Bragg contri... more The use of bright field TEM for tomography in physical sciences is often hampered by Bragg contributions. In Figure 1 it is illustrated that the morphology of Pt nanoparticles (5-7 nm) is well reconstructed, but artificial cavities are observed inside the 3D reconstructions of the ...
MRS Proceedings, 2004
ABSTRACTIn this study we examine the immediate interface between matrix grains and the amorphous ... more ABSTRACTIn this study we examine the immediate interface between matrix grains and the amorphous intergranular film in a Si3N4 ceramic doped with rare-earth oxides La2O3, Sm2O3, Er2O3, Yb2O3 and Lu2O3, extracting unique structural and atomic bonding information. In particular, we relate the structure of the interface to the ionic size and electronic structure of the rare-earth elements and the presence of oxygen in the intergranular film. We relate these results to the measured fracture toughness.
Microscopy and Microanalysis, 2014
Science, 2009
Although the physics of materials at surfaces and edges has been extensively studied, the movemen... more Although the physics of materials at surfaces and edges has been extensively studied, the movement of individual atoms at an isolated edge has not been directly observed in real time. With a transmission electron aberration–corrected microscope capable of simultaneous atomic spatial resolution and 1-second temporal resolution, we produced movies of the dynamics of carbon atoms at the edge of a hole in a suspended, single atomic layer of graphene. The rearrangement of bonds and beam-induced ejection of carbon atoms are recorded as the hole grows. We investigated the mechanism of edge reconstruction and demonstrated the stability of the “zigzag” edge configuration. This study of an ideal low-dimensional interface, a hole in graphene, exhibits the complex behavior of atoms at a boundary.
Physical Review Letters, 2011
Physica B: Condensed Matter, 2006
Microscopy and Microanalysis, 2007
Extended abstract of a paper presented at Microscopy and Microanalysis 2007 in Ft. Lauderdale, Fl... more Extended abstract of a paper presented at Microscopy and Microanalysis 2007 in Ft. Lauderdale, Florida, USA, August 5 – August 9, 2007
Microscopy and Microanalysis, 2005
Microscopy and Microanalysis, 2005