Experimental Implications of X-Ray Standing Waves

2014 ◽  
pp. 462-482
Keyword(s):  
Absorption Coefficient ◽  
Standing Waves ◽  
Anomalous Absorption ◽  
X Ray Diffraction ◽  
Linear Absorption Coefficient ◽  
Linear Absorption ◽  
X Ray ◽  
Basic Concepts

Basic concepts of dynamic X-ray diffraction are applied in distinguishing between the propagation along the atomic planes characterized by the linear absorption coefficient and the perpendicular propagation on the atomic planes. Propagation is responsible for the generation of the standing waves through the anomalous absorption coefficient on dispersion branches of diffraction.

The crystal structure of o-(1,2-dicarba-closo-dodecaborane-1-yl)methyl-cholesterol

1991 ◽  
Vol 56 (10) ◽  
pp. 1983-1992 ◽  
Author(s):  
Věra Šubrtová ◽  
Václav Petříček ◽  
Karel Malý
Keyword(s):  
Room Temperature ◽  
Valence Angle ◽  
X Ray Diffraction ◽  
Linear Absorption Coefficient ◽  
Unit Cell Parameters ◽  
Linear Absorption ◽  
Calculated Density ◽  
X Ray ◽  
Cell Parameters ◽  
Temperature Radiation

The structure of C2B10H11.CH2C27H45O was determined by X-ray diffraction. This compound crystallizes in the orthorhombic system with the P212121 space group. The unit cell parameters are a = 994.0(4), b = 3 231.0(7), c = 1 039.6(2) pm, V = 3 338 . 106 pm3, Z = 4, calculated density Dc = 1.080Mg m-3. Mr = 542.9, linear absorption coefficient μ(MoK α) = 0.54 cm-1 F(000) = 1 184. Intensities were measured at room temperature, radiation used λ(MoK α) = 71.073 pm. Final R = 0.063 for 2 099 observed independent reflections. The studied molecule is built from ortho-carborane icosahedron connected with the cholesterol through the methylene CH2 group bonded to the icosahedral carbon atom C(B1) (C-C= 151.0(7) pm) and to the oxygen atom of the cholesterol (C-O = 138.3(7) pm). Valence angle C(B1)-C-O = 108(2)°, torsion angle C(B1)-C-O-C(3) = 164(4)°.

scholarly journals Directly observing intracellular nanoparticle formation with nanocomputed tomography

2020 ◽  
Vol 6 (43) ◽  
pp. eaba3190
Author(s):  
Miaomiao Zhang ◽  
Yong Guan ◽  
Zheng Dang ◽  
Pinggen Zhang ◽  
Zhen Zheng ◽  
...  
Keyword(s):  
Absorption Coefficient ◽  
Small Molecule ◽  
Hela Cells ◽  
Condensation Reaction ◽  
Linear Absorption Coefficient ◽  
Linear Absorption ◽  
X Ray ◽  
Nanoparticle Formation ◽  
Near Future

Directly observing intracellular nanostructure formation remains challenging. In this work, using a rationally designed small-molecule 4-nitrobenzyl carbamate–Cys(SEt)-Asp-Asp-Phe(iodine)–2-cyano-benzothiazole (NBC-Iod-CBT), we directly observed intracellular nanoparticle formation with nanocomputed tomography (nano-CT). In vitro, upon glutathione reduction and nitroreductase (NTR) cleavage, NBC-Iod-CBT undergoes a CBT-Cys click condensation reaction to self-assemble nanoparticles Iod-CBT-NPs with an average linear absorption coefficient (LAC) value of 0.182 ± 0.078 μm−1 to x-ray. Nano-CT imaging of the NBC-Iod-CBT–treated, NTR-overexpressing HeLa cells showed the existence of Iod-CBT-NPs in their cytoplasm with an average LAC value of 0.172 ± 0.032 μm−1. We anticipate that our strategy could help people to deeply understand the formation mechanism of intracellular nanostructures in the near future.

scholarly journals Ta Doping Effect on Structural and Optical Properties of InTe Thin Films

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1887
Author(s):  
Chunmin Liu ◽  
Yafei Yuan ◽  
Xintong Zhang ◽  
Jing Su ◽  
Xiaoxiao Song ◽  
...  
Keyword(s):  
Thin Films ◽  
Absorption Coefficient ◽  
Doping Concentration ◽  
Photon Absorption ◽  
X Ray Diffraction ◽  
Linear Absorption ◽  
X Ray ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Ta Doping

The objective of this work was to study the influence of Ta doping on the structural, transmittance properties, linear absorption parameter, and nonlinear absorption properties of InTe thin films. The as-deposited samples with different Ta doping concentrations were prepared by a magnetron co-sputtering technique and then annealed in nitrogen atmosphere. Structural investigations by X-ray diffraction revealed the tetragonal structure of InTe samples and that the crystallinity decreases with increasing Ta doping concentration. Further structural analysis by Raman spectra also showed good agreement with X-ray diffraction results. The Ta doping concentration and sample thickness determined by energy-dispersive X-ray spectroscopy and scanning electron microscopy increased as Ta dopant increased. In addition, X-ray photoelectron spectroscopic was carried out to analyze the chemical states of the elements. UV–VIS–NIR transmittance spectra were applied to study the transmittance properties and calculate the linear absorption coefficient. Due to Burstein–Moss effect, the absorption edge moved to shorter wavelengths. Meanwhile, the values of band gap were found to increase from 1.71 ± 0.02 eV to 1.85 ± 0.01 eV with the increase of Ta doping concentration. By performing an open aperture Z-scan technique, we found that all Ta-doped InTe samples exhibited two-photon absorption behaviors. The nonlinear optical absorption parameters, such as modulation depth, two-photon absorption coefficient, and two-photon absorption cross-section, decrease with increasing Ta concentration, whereas the damage threshold increases from 176 ± 0.5 GW/cm2 to 242 ± 0.5 GW/cm2. These novel properties show the potential for applications in traditional optoelectronic devices and optical limiters.

An X-Ray Absorption Technique for Measurement of Coat Weight on Paper

1960 ◽  
Vol 4 ◽  
pp. 309-318
Author(s):  
Haydn H. Murray ◽  
William D. Johns
Keyword(s):  
Absorption Coefficient ◽  
Production Control ◽  
Absorption Method ◽  
Linear Absorption Coefficient ◽  
Linear Absorption ◽  
Absorbing Medium ◽  
X Ray ◽  
Coating Layers ◽  
X Ray Absorption ◽  
Absorption Technique

AbstractAn X-ray absorption method was utilized to determine rapidly and precisely the thickness and weight of inorganic coating layers applied to paper. The mass absorption coefficient μ/ρ was calculated for kaolins and substituted in the following formulawhere I is the X-ray intensity after passing through a medium whose thickness is x centimeters, I0 Is the X-ray intensity before passing through a medium, μ. is the linear absorption coefficient, and ρ is the density of the absorbing medium.The film thickness was calculated and related to coat weight. Coated sheets of variable basis weight, utilizing different adhesives and coat weights, were used. The method is rapid and coating thicknesses can be determined with an accuracy of plus or minus 0.5μ and coat weight of plus or minus 0.2 lb. It is believed that the method can be adapted for production control on the paper coating machines.

New developments including X-ray standing waves in the dynamical Bragg diffraction program of X-ray Server

2021 ◽  
Vol 54 (5) ◽  
pp. 1530-1534
Author(s):  
Sergey Stepanov
Keyword(s):  
Standing Waves ◽  
Grazing Incidence ◽  
Bragg Diffraction ◽  
Use Cases ◽  
X Ray Diffraction ◽  
New Developments ◽  
Dynamical Diffraction ◽  
X Ray

X-ray Server (https://x-server.gmca.aps.anl.gov) is a collection of programs for online modelling of X-ray diffraction and scattering. The dynamical diffraction program is the second most popular Server program, contributing 34% of total Server usage. It models dynamical X-ray diffraction from strained crystals and multilayers for any Bragg-case geometry including grazing incidence and exit. This paper reports on a revision of equations used by the program, which yields ten times faster calculations in most use cases, on implementing calculations of X-ray standing waves and on adding new options for modelling diffraction from monolayers.

Absorption Coefficients of Inelastic Dynamic X-Ray Diffraction

2014 ◽  
pp. 483-502
Keyword(s):  
Absorption Coefficient ◽  
Inelastic Scattering ◽  
Waller Factor ◽  
Time Dependent ◽  
X Ray Diffraction ◽  
Absorption Coefficients ◽  
X Ray ◽  
Charge Current ◽  
Dispersion Equations ◽  
Debye Waller Factor

The X-ray inelastic scattering phenomena during the time-dependent perturbations are described with the aid of dynamical dispersion equations coupled with charge current in the Maxwell equations towards the appearance of the Debye-Waller factor driving the absorption coefficient, either for inelastic thermal diffusion and the Compton scattering, respectively.

Measurement of Mass Absorption Coefficients Using Compton-Scattered Cu Radiation in X-ray Diffraction Analysis

1990 ◽  
Vol 34 ◽  
pp. 325-335 ◽  
Author(s):  
Steve J. Chipera ◽  
David L. Bish
Keyword(s):  
Chemical Composition ◽  
Solid State ◽  
Absorption Coefficient ◽  
Mass Absorption Coefficient ◽  
X Rays ◽  
X Ray Diffraction ◽  
Absorption Coefficients ◽  
Solid State Detector ◽  
X Ray ◽  
Mass Absorption

AbstractThe mass absorption coefficient is a useful parameter for quantitative characterization of materials. If the chemical composition of a sample is known, the mass absorption coefficient can be calculated directly. However, the mass absorption coefficient must be determined empirically if the chemical composition is unknown. Traditional methods for determining the mass absorption coefficient involve measuring the transmission of monochromatic X-rays through a sample of known thickness and density. Reynolds (1963,1967), however, proposed a method for determining the mass absorption coefficient by measuring the Compton or inelastic X-ray scattering from a sample using Mo radiation on an X-ray fluorescence spectrometer (XRF). With the recent advances in solid-state detectors/electronics for use with conventional powder diffractometers, it is now possible to readily determine mass absorption coefficients during routine X-ray diffraction (XRD) analyses.Using Cu Kα radiation and Reynolds’ method on a Siemens D-500 diffractometer fitted with a Kevex Si(Li) solid-state detector, we have measured the mass absorption coefficients of a suite of minerals and pure chemical compounds ranging in μ/ρ from graphite to Fe-metal (μ/ρ = 4.6-308 using Cu Kα radiation) to ±4.0% (lσ). The relationship between the known mass absorption coefficient and the inverse count rate is linear with a correlation coefficient of 0.997. Using mass absorption coefficients, phase abundances can be determined during quantitative XRD analysis without requiring the use of an internal standard, even when an amorphous component is present.

Sign in / Sign up

Export Citation Format

Share Document