X-Ray Spectroscopic Studies of Organo-Metallic Vapor Phase Epitaxial Growth

1993 ◽  
Vol 312 ◽  
Author(s):  
S. Brennant ◽  
P. H. Fuosst ◽  
D. W. Kisker ◽  
F. J. Lamelast ◽  
P. Imperatori ◽  
...  
Keyword(s):  
Film Growth ◽  
Chemical Vapor ◽  
Spectroscopic Studies ◽  
Reactor Vessel ◽  
X Rays ◽  
X Ray ◽  
Structural Probe ◽  
X Ray Absorption ◽  
Structural Probes ◽  
Metallic Vapor

AbstractChemical Vapor Deposition often occurs under conditions unsuitable for simultaneous monitoring using electron-based structural probes. This is due to the near-atmospheric pressure which exists during growth. While some work has been performed using optical probes, the typically high temperatures in the reactor vessel and the vastly longer wavelength of visible light versus the features being studied has hampered its utility as a structural probe. Over the past several years x-rays from synchrotron storage rings have been used to study the surface structure of growing materials. These studies have been primarily scattering studies. In this paper we explore the use of x-ray spectroscopic studies for the analysis of film growth. We have focused on three areas: the measurement of reactor vessel profiles using x-ray fluorescence; The measurement of gas-phase Extended X-ray Absorption Fine Structure (EXAFS), and the measurement of EXAFS of adsorbed species on the substrates.

X-RAY ABSORPTION SPECTROSCOPY STUDY OF THIN ZnO FILMS GROWN BY SINGLE SOURCE CVD ON Si(100)

1997 ◽  
Vol 04 (01) ◽  
pp. 39-44 ◽  
Author(s):  
M. H. KOCH ◽  
A. J. HARTMANN ◽  
R. N. LAMB ◽  
M. NEUBER ◽  
J. WALZ ◽  
...  
Keyword(s):  
Film Thickness ◽  
Absorption Spectroscopy ◽  
Film Growth ◽  
Chemical Vapor ◽  
Zno Films ◽  
Single Source ◽  
Zno Film ◽  
High Concentration ◽  
X Ray ◽  
X Ray Absorption

In situ X-ray absorption spectroscopy analysis of early states of ZnO film growth on Si(100) by single source chemical vapor deposition (CVD) has been performed using basic zinc acetate as precursor. A high concentration of carbon is detected at the interface, which decreases with increasing film thickness (~2 nm thickness), and as expected there is some oxidization of the Si surface. This is explained by the chemical nature of the immediate surface upon which the deposition takes place, varying from a reactive, clean Si surface to a less reactive, mixed oxide layer after successive deposition steps. On the latter surface, the decomposition fragments are believed to be more volatile and thus the resulting film contains less carbon contamination. The results confirm that the tetrahedral core of the central oxygen atom with four neighboring zinc atoms, which reassembles the structure in solid ZnO , is kept intact upon decomposition of the precursor on the heated Si (100) (400°C) substrate. However, no long range orientation of the ZnO tetrahedrons was found, indicating that the resulting ZnO film has no preferred crystalline structure for the film thickness investigated here (~2 nm).

X-Ray absorption edge elemental imaging of B. thuringienis

1989 ◽  
Vol 47 ◽  
pp. 212-213
Author(s):  
R. L. Stears
Keyword(s):  
Absorption Edge ◽  
Elemental Distribution ◽  
X Rays ◽  
Differential Absorption ◽  
Synchrotron Source ◽  
High Brightness ◽  
X Ray ◽  
Elemental Imaging ◽  
Cellular Integrity ◽  
X Ray Absorption

Because of the nature of the bacterial endospore, little work has been done on analyzing their elemental distribution and composition in the intact, living, hydrated state. The majority of the qualitative analysis entailed intensive disruption and processing of the endospores, which effects their cellular integrity and composition.Absorption edge imaging permits elemental analysis of hydrated, unstained specimens at high resolution. By taking advantage of differential absorption of x-ray photons in regions of varying elemental composition, and using a high brightness, tuneable synchrotron source to obtain monochromatic x-rays, contact x-ray micrographs can be made of unfixed, intact endospores that reveal sites of elemental localization. This study presents new data demonstrating the application of x-ray absorption edge imaging to produce elemental information about nitrogen (N) and calcium (Ca) localization using Bacillus thuringiensis as the test specimen.

scholarly journals Al-driven peculiarities of local coordination and magnetic properties in single-phase Alx-CrFeCoNi high-entropy alloys

Nano Research ◽  
2021 ◽  
Author(s):  
Alevtina Smekhova ◽  
Alexei Kuzmin ◽  
Konrad Siemensmeyer ◽  
Chen Luo ◽  
Kai Chen ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Single Phase ◽  
Magnetic Circular Dichroism ◽  
Surface Region ◽  
Face Centered Cubic ◽  
X Rays ◽  
X Ray ◽  
High Entropy ◽  
X Ray Absorption ◽  
Absorption Edges

AbstractModern design of superior multi-functional alloys composed of several principal components requires in-depth studies of their local structure for developing desired macroscopic properties. Herein, peculiarities of atomic arrangements on the local scale and electronic states of constituent elements in the single-phase face-centered cubic (fcc)- and body-centered cubic (bcc)-structured high-entropy Alx-CrFeCoNi alloys (x = 0.3 and 3, respectively) are explored by element-specific X-ray absorption spectroscopy in hard and soft X-ray energy ranges. Simulations based on the reverse Monte Carlo approach allow to perform a simultaneous fit of extended X-ray absorption fine structure spectra recorded at K absorption edges of each 3d constituent and to reconstruct the local environment within the first coordination shells of absorbers with high precision. The revealed unimodal and bimodal distributions of all five elements are in agreement with structure-dependent magnetic properties of studied alloys probed by magnetometry. A degree of surface atoms oxidation uncovered by soft X-rays suggests different kinetics of oxide formation for each type of constituents and has to be taken into account. X-ray magnetic circular dichroism technique employed at L2.3 absorption edges of transition metals demonstrates reduced magnetic moments of 3d metal constituents in the sub-surface region of in situ cleaned fcc-structured Al0.3-CrFeCoNi compared to their bulk values. Extended to nanostructured versions of multicomponent alloys, such studies would bring new insights related to effects of high entropy mixing on low dimensions.

scholarly journals Synchrotron X-ray induced acoustic imaging

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Seongwook Choi ◽  
Eun-Yeong Park ◽  
Sinyoung Park ◽  
Jong Hyun Kim ◽  
Chulhong Kim
Keyword(s):  
Acoustic Imaging ◽  
Signal Frequency ◽  
X Rays ◽  
Repetition Period ◽  
Linear Accelerators ◽  
X Ray ◽  
X Ray Computed ◽  
Medical Linear Accelerators ◽  
Ionizing Radiation Exposure ◽  
X Ray Absorption

AbstractX-ray induced acoustic imaging (XAI) is an emerging biomedical imaging technique that can visualize X-ray absorption contrast at ultrasound resolution with less ionizing radiation exposure than conventional X-ray computed tomography. So far, medical linear accelerators or industrial portable X-ray tubes have been explored as X-ray excitation sources for XAI. Here, we demonstrate the first feasible synchrotron XAI (sXAI). The synchrotron generates X-rays, with a dominant energy of 4 to 30 keV, a pulse-width of 30 ps, a pulse-repetition period of 2 ns, and a bunch-repetition period of 940 ns. The X-ray induced acoustic (XA) signals are processed in the Fourier domain by matching the signal frequency with the bunch-repetition frequency. We successfully obtained two-dimensional XA images of various lead targets. This novel sXAI tool could complement conventional synchrotron applications.

X-ray Absorption Fine Structure Spectroscopic Studies of Octakis(DMSO)lanthanoid(III) Complexes in Solution and in the Solid Iodides

2007 ◽  
Vol 46 (19) ◽  
pp. 7742-7748 ◽  
Author(s):  
Ingmar Persson ◽  
Emiliana Damian Risberg ◽  
Paola D'Angelo ◽  
Simone De Panfilis ◽  
Magnus Sandström ◽  
...  
Keyword(s):  
Fine Structure ◽  
Spectroscopic Studies ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption

scholarly journals Semi-automated protein crystal mounting device for the sulfur single-wavelength anomalous diffraction method

2010 ◽  
Vol 43 (2) ◽  
pp. 341-346 ◽  
Author(s):  
Yu Kitago ◽  
Nobuhisa Watanabe ◽  
Isao Tanaka
Keyword(s):  
Diffraction Method ◽  
Systematic Errors ◽  
Protein Crystal ◽  
X Rays ◽  
Anomalous Diffraction ◽  
X Ray ◽  
Frozen Solution ◽  
Custom Made ◽  
Protein Molecules ◽  
X Ray Absorption

Use of longer-wavelength X-rays has advantages for the detection of small anomalous signals from light atoms, such as sulfur, in protein molecules. However, the accuracy of the measured diffraction data decreases at longer wavelengths because of the greater X-ray absorption. The capillary-top mounting method (formerly the loopless mounting method) makes it possible to eliminate frozen solution around the protein crystal and reduces systematic errors in the evaluation of small anomalous differences. However, use of this method requires custom-made tools and a large amount of skill. Here, the development of a device that can freeze the protein crystal semi-automatically using the capillary-top mounting method is described. This device can pick up the protein crystal from the crystallization drop using a micro-manipulator, and further procedures, such as withdrawal of the solution around the crystal by suction and subsequent flash freezing of the protein crystal, are carried out automatically. This device makes it easy for structural biologists to use the capillary-top mounting method for sulfur single-wavelength anomalous diffraction phasing using longer-wavelength X-rays.

A soft X-ray absorption study of nanodiamond films prepared by hot-filament chemical vapor deposition

2003 ◽  
Vol 372 (3-4) ◽  
pp. 320-324 ◽  
Author(s):  
Y.H Tang ◽  
X.T Zhou ◽  
Y.F Hu ◽  
C.S Lee ◽  
S.T Lee ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Absorption Study ◽  
X Ray ◽  
Hot Filament ◽  
X Ray Absorption
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