scholarly journals Carbon clusters formed from shocked benzene

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
D. M. Dattelbaum ◽  
E. B. Watkins ◽  
M. A. Firestone ◽  
R. C. Huber ◽  
R. L. Gustavsen ◽  
...  
Keyword(s):  
High Pressures ◽  
Complex Mixture ◽  
Carbon Clusters ◽  
X Rays ◽  
Reaction Products ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Liquid Benzene ◽  
X Ray Scattering

AbstractBenzene (C6H6), while stable under ambient conditions, can become chemically reactive at high pressures and temperatures, such as under shock loading conditions. Here, we report in situ x-ray diffraction and small angle x-ray scattering measurements of liquid benzene shocked to 55 GPa, capturing the morphology and crystalline structure of the shock-driven reaction products at nanosecond timescales. The shock-driven chemical reactions in benzene observed using coherent XFEL x-rays were a complex mixture of products composed of carbon and hydrocarbon allotropes. In contrast to the conventional description of diamond, methane and hydrogen formation, our present results indicate that benzene’s shock-driven reaction products consist of layered sheet-like hydrocarbon structures and nanosized carbon clusters with mixed sp2-sp3 hybridized bonding. Implications of these findings range from guiding shock synthesis of novel compounds to the fundamentals of carbon transport in planetary physics.

Stable Pt/Ge/Au Ohmic Contact to N-GaAs with a Ta-Si-N Barrier

1993 ◽  
Vol 300 ◽  
Author(s):  
J. S. Chen ◽  
E. Kolawa ◽  
R. P. Ruiz ◽  
M-A. Nicolet
Keyword(s):  
Barrier Layer ◽  
Main Reaction ◽  
X Rays ◽  
Reaction Products ◽  
X Ray Diffraction ◽  
Semiconductor Interface ◽  
Rich Phase ◽  
X Ray ◽  
Thermal Reactions ◽  
Transmission Electron

ABSTRACTA Pt/Ge/Au contact of the structure: <n-GaAs>/Pt(17nm)/Ge(25nm)/Au(43nm), overlaid with a Ta-Si-N barrier layer and a Au metallization layer has a contact resistivity, ρc, of 3.7×10−6 Ωcm2 after annealing at 450°C for 15 min. After aging at 450°C for 60 h, ρc slightly degrades to 5.5×10−6 Ωcm2 while the surface keeps smooth. When alloyed at 550°C for 15 min, ρc is 1.8×10−6 Ωcm2 and stays about the same value after annealing at 550°C for 1 h. Without the Ta-Si-N barrier and the Au overlayer, the Pt/Ge/Au contact alone is also ohmic after annealing at 450°C for 15 min but with a ρc of ∼10−5 Ωcm2 while the surface morphology deteriorates significantly after aging at 450°C for 20 h.The thermal reactions of this Pt/Ge/Au contact on GaAs, with or without a Ta-Si-N barrier layer, are investigated by backscattering spectrometry, x-ray diffraction, and transmission electron microscopy in conjunction with energy dispersive analyses of x-rays. For all samples, the main reaction products after annealing at 450°C for 15 min are Au7Ga2, and PtGe:As, a PtGe phase that also contains arsenic. The product phases are randomly distributed within a laterally uniform reacted layer when the Pt/Ge/Au contact is covered by a Ta-Si-N layer. Without the Ta-Si-N barrier layer, a small arsenic loss and a Ga-rich phase (probably Gaoxides) on the contact surface are observed after annealing at 450°C. In this case, the surface and contact-semiconductor interface are more faceted than with a Ta-Si-N barrier layer.

Towards high-flux X-ray beam compressing channel-cut monochromators

2016 ◽  
Vol 49 (6) ◽  
pp. 1885-1892 ◽  
Author(s):  
Karol Végsö ◽  
Matej Jergel ◽  
Peter Šiffalovič ◽  
Eva Majková ◽  
Dušan Korytár ◽  
...  
Keyword(s):  
Compression Ratio ◽  
Single Point ◽  
Grazing Incidence ◽  
High Flux ◽  
X Rays ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Scattering ◽  
Medium Resolution ◽  
Experimental Resolution

The issue of a high-flux X-ray beam compressing channel-cut monochromator for applications in X-ray metrology is addressed. A Ge(111) compressor with compression ratio 20.3 was designed on the principle of a combination of symmetric and highly asymmetric diffractions. A pilot application of the single-point diamond technology (SPDT) to finish active surfaces of X-ray optics was tested, providing 50% flux enhancement as compared to a Ge(220) counterpart prepared by traditional surface treatment. This is much more than the theoretical 22% forecast and shows the potential of SPDT for preparation of high-flux X-ray compressors with a high compression ratio, where highly asymmetric diffraction with a very low exit angle is inevitable. The implications for efficient collection of X-rays from microfocus X-ray sources are discussed. A comparison of Ge compressors with Ge parallel channel-cut monochromators combined with a 50 µm slit shows the several times higher flux of the former, making them applicable in X-ray diffraction experiments at medium resolution. Furthermore, the Ge(111) compressor was tested as a collimator in high-resolution grazing-incidence small-angle X-ray scattering (GISAXS) measurements of surface gratings, providing experimental resolution close to 400 nm. This is ∼100 nm smaller than that achieved with the Ge(220) compressor but still approximately twice that of commercial SAXS/GISAXS laboratory setups.

scholarly journals High Pressure Diffraction for the Geosciences at the Advanced Light Source

2014 ◽  
Vol 70 (a1) ◽  
pp. C1097-C1097
Author(s):  
Christine Beavers ◽  
Jason Knight ◽  
Bora Kalkan ◽  
Jinyuan Yan ◽  
Alastair MacDowell ◽  
...  
Keyword(s):  
High Pressure ◽  
Light Source ◽  
High Pressures ◽  
X Rays ◽  
X Ray Diffraction ◽  
User Friendliness ◽  
X Ray ◽  
Advanced Light Source ◽  
Diamond Anvil ◽  
Multiple Detectors

The Advanced Light Source, in concert with COMPRES, supports a superconducting bending magnet beamline devoted to extreme conditions diffraction. This facility, beamline 12.2.2, is aimed at the geoscience community, but is available to any who desire high pressures, high temperatures and hard X-rays. The latest development has been integrating single crystal x-ray diffraction for diamond anvil cells into the existing suite of high pressure powder diffraction and amorphous scattering techniques. Multiple heating techniques are available to the user, as well as multiple detectors, which can be chosen to best suit the sample. The current staff are dedicated to improving the user friendliness of the beamline; a difficult experiment need not to be further complicated by a difficult beamline. Beamline infrastructure, including recent advances and improvements, will be discussed.

scholarly journals Grating-based holographic diffraction methods for X-rays and neutrons: phase object approximation and dynamical theory

2018 ◽  
Vol 51 (1) ◽  
pp. 68-75 ◽  
Author(s):  
Hao Feng ◽  
Rana Ashkar ◽  
Nina Steinke ◽  
Robert Dalgliesh ◽  
Nickolay V. Lavrik ◽  
...  
Keyword(s):  
Spin Echo ◽  
Dynamical Theory ◽  
X Rays ◽  
Phase Approximation ◽  
X Ray Diffraction ◽  
Colloidal Structure ◽  
X Ray ◽  
X Ray Scattering ◽  
Weak Phase ◽  
Colloidal Fluids

A method dubbed grating-based holography was recently used to determine the structure of colloidal fluids in the rectangular grooves of a diffraction grating from X-ray scattering measurements. Similar grating-based measurements have also been recently made with neutrons using a technique called spin-echo small-angle neutron scattering. The analysis of the X-ray diffraction data was done using an approximation that treats the X-ray phase change caused by the colloidal structure as a small perturbation to the overall phase pattern generated by the grating. In this paper, the adequacy of this weak phase approximation is explored for both X-ray and neutron grating holography. It is found that there are several approximations hidden within the weak phase approximation that can lead to incorrect conclusions from experiments. In particular, the phase contrast for the empty grating is a critical parameter. While the approximation is found to be perfectly adequate for X-ray grating holography experiments performed to date, it cannot be applied to similar neutron experiments because the latter technique requires much deeper grating channels.

scholarly journals Synthesis of magnesium-nitrogen salts of polynitrogen anions

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Dominique Laniel ◽  
Bjoern Winkler ◽  
Egor Koemets ◽  
Timofey Fedotenko ◽  
Maxim Bykov ◽  
...  
Keyword(s):  
High Pressures ◽  
Molecular Nitrogen ◽  
High Energy ◽  
High Energy Density ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Energy Density Materials ◽  
Polynitrogen Compounds ◽  
Laser Heated

Abstract The synthesis of polynitrogen compounds is of fundamental importance due to their potential as environmentally-friendly high energy density materials. Attesting to the intrinsic difficulties related to their formation, only three polynitrogen ions, bulk stabilized as salts, are known. Here, magnesium and molecular nitrogen are compressed to about 50 GPa and laser-heated, producing two chemically simple salts of polynitrogen anions, MgN4 and Mg2N4. Single-crystal X-ray diffraction reveals infinite anionic polythiazyl-like 1D N-N chains in the crystal structure of MgN4 and cis-tetranitrogen N44− units in the two isosymmetric polymorphs of Mg2N4. The cis-tetranitrogen units are found to be recoverable at atmospheric pressure. Our results respond to the quest for polynitrogen entities stable at ambient conditions, reveal the potential of employing high pressures in their synthesis and enrich the nitrogen chemistry through the discovery of other nitrogen species, which provides further possibilities to design improved polynitrogen arrangements.

X-ray Scattering from Interfaces

1991 ◽  
Vol 237 ◽  
Author(s):  
E. Vlieg ◽  
H. A. Van Der Vegt
Keyword(s):  
Epitaxial Growth ◽  
Surface Structures ◽  
X Rays ◽  
X Ray Diffraction ◽  
General Outline ◽  
X Ray ◽  
Buried Interfaces ◽  
X Ray Scattering ◽  
High Penetration

ABSTRACTX-ray diffraction has found an increasing use in the characterization of surface structures. Due to the high penetration depth of X-rays, the technique is also very suitable for the study of buried interfaces. We will give a general outline of the technique, and then discuss two examples concerning epitaxial growth.

High-quality structures at high pressure? Insights from inclusions in diamonds

2016 ◽  
Vol 231 (8) ◽  
Author(s):  
Ross J. Angel ◽  
Sula Milani ◽  
Matteo Alvaro ◽  
Fabrizio Nestola
Keyword(s):  
High Pressure ◽  
Single Crystal ◽  
High Pressures ◽  
Dominant Factor ◽  
Good Precision ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Experimental Protocols ◽  
Diamond Anvil

AbstractWe describe the experimental protocols necessary to measure the crystal structures of minerals trapped within diamonds by single-crystal X-ray diffraction to the same quality as obtained from minerals studied at ambient conditions. The results show that corrections for X-ray absorption in complex cases can be made with good precision. Comparison of the refined structure of a single-crystal olivine inclusion inside a diamond with the structure of a similar olivine held in a high-pressure diamond-anvil cell shows that data resolution, not the correction for absorption effects, is the dominant factor in influencing the quality of structures determined at high pressures by single-crystal X-ray diffraction.

The Interaction of Bio-Molecules with Lipid Membranes Studied by X-ray Diffraction

2014 ◽  
Vol 228 (10-12) ◽  
Author(s):  
Maikel Rheinstädter ◽  
Laura Toppozini ◽  
Hannah Dies
Keyword(s):  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Quantitative Information ◽  
X Rays ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Scattering ◽  
Molecular Ordering ◽  
Indispensable Tool

AbstractFor the past 100 years, X-ray diffraction has been a powerful and indispensable tool to study the structure of matter. The challenge when studying molecular ordering in biological materials is their inherent disorder and strong fluctuations, which often suppress the formation of Bragg peaks. In the case of membranes, X-rays can detect molecules inside and confined between membranes. In this article we review examples to highlight the capabilities and accomplishments of X-ray scattering for the determination of membrane structure. X-ray diffraction gives quantitative information about partitioning of a small molecule, ethanol, in lipid bilayers. By taking amyloid-

XDS: a flexible beamline for X-ray diffraction and spectroscopy at the Brazilian synchrotron

2016 ◽  
Vol 23 (6) ◽  
pp. 1538-1549 ◽  
Author(s):  
F. A. Lima ◽  
M. E. Saleta ◽  
R. J. S. Pagliuca ◽  
M. A. Eleotério ◽  
R. D. Reis ◽  
...  
Keyword(s):  
High Pressures ◽  
Materials Science ◽  
Photon Flux ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Scattering ◽  
Science Community ◽  
Synchrotron Light ◽  
X Ray Absorption ◽  
Photon Source

The majority of the beamlines at the Brazilian Synchrotron Light Source Laboratory (LNLS) use radiation produced in the storage-ring bending magnets and are therefore currently limited in the flux that can be used in the harder part of the X-ray spectrum (above ∼10 keV). A 4 T superconducting multipolar wiggler (SCW) was recently installed at LNLS in order to improve the photon flux above 10 keV and fulfill the demands set by the materials science community. A new multi-purpose beamline was then installed at the LNLS using the SCW as a photon source. The XDS is a flexible beamline operating in the energy range between 5 and 30 keV, designed to perform experiments using absorption, diffraction and scattering techniques. Most of the work performed at the XDS beamline concentrates on X-ray absorption spectroscopy at energies above 18 keV and high-resolution diffraction experiments. More recently, new setups and photon-hungry experiments such as total X-ray scattering, X-ray diffraction under high pressures, resonant X-ray emission spectroscopy, among others, have started to become routine at XDS. Here, the XDS beamline characteristics, performance and a few new experimental possibilities are described.

scholarly journals Phase I Beamlines at Taiwan Photon Source

2014 ◽  
Vol 70 (a1) ◽  
pp. C1740-C1740
Author(s):  
Shih-Chun Chung ◽  
Mau-Tsu Tang ◽  
Yu-Shan Huang ◽  
Chia-Hung Hsu ◽  
Di-Jing Huang ◽  
...  
Keyword(s):  
Phase I ◽  
Large Scale ◽  
X Rays ◽  
Photon Beams ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Scattering ◽  
Synchrotron Facility ◽  
Photon Source ◽  
Ray Scattering

With rapid advances in the international scientific community as well as increasing demands for bright X-rays from users to facilitate their challenging scientific experiments, the construction of a new synchrotron facility was vital to maintaining National Synchrotron Radiation Research Center in Taiwan to be globally competitive. After conducting numerous assessments with our users, the decision to construct Taiwan Photon Source (TPS) was made at the meeting of Board of Trustee held in 2004 July. This large-scale project will establish, at the current campus of NSRRC, a new, low-emittance, synchrotron light source of circumference 518 m and with an electron beam of energy 3 GeV. TPS is designed to emphasize electron beams of small emittance and great brilliance for generating extremely bright photon beams. The superior characteristics of TPS have opened avenues for novel scientific opportunities and experimental techniques. The advanced techniques of phase-I beamlines include temporally coherent X-ray diffraction, protein microcrystollography, submicron soft X-ray spectroscopy, coherent X-ray scattering, submicron X-ray diffraction, X-ray nanoprobe, and high resolution inelastic soft X-ray scattering. Taking full advantage of the highly brilliant photon source, the seven planned beamline will aim for the forefront of science. These beamlines cover diverse research in physics, chemistry, biology, and material science, in the energy range from soft to hard X-rays for advanced research in spectroscopy, scattering and imaging.

Sign in / Sign up

Export Citation Format

Share Document