Investigation of Lithium Precipitates in Germanium Crystals by Anomalous X-Ray Transmission

1971 ◽  
Vol 26 (3) ◽  
pp. 495-501 ◽  
Author(s):  
Helmut F. Wenzl
Keyword(s):  
Phase Diagram ◽  
Absorption Coefficient ◽  
Local Concentration ◽  
X Rays ◽  
Effective Absorption Coefficient ◽  
Pair Correlations ◽  
X Ray ◽  
Effective Absorption ◽  
Anomalous Transmission ◽  
Distortion Parameters

Abstract The precipitation of lithium dissolved in germanium crystals and the re-solution of the precipitates during heating has been studied by means of anomalous transmission of x-rays. The effective absorption coefficient depends sensitively on the spacial distribution of lithium interstitials, and is enhanced enormously if pair correlations increase, as is the case during clustering. On the basis of Dederidis' theory and knowledge about the Geli phase diagram, the experiments provide relations between concentration and radius of the precipitates, distortion parameters, and average and local concentration of lithium interstitials.

Dependence of X-ray plane-wave rocking curves on the deviation from exact Bragg orientation in and perpendicular to the diffraction plane for the asymmetrical Laue case

2018 ◽  
Vol 74 (3) ◽  
pp. 204-215 ◽  
Author(s):  
Minas K. Balyan
Keyword(s):  
Plane Wave ◽  
Absorption Coefficient ◽  
Wave Transmission ◽  
Reflection Coefficients ◽  
Effective Absorption Coefficient ◽  
Diffraction Plane ◽  
X Ray ◽  
Transmission And Reflection Coefficients ◽  
Effective Absorption ◽  
Transmission And Reflection

For the asymmetrical Laue case the X-ray plane-wave transmission and reflection coefficients and rocking curves are analysed as a function of the deviation angles from the exact Bragg orientation in the diffraction plane and in the direction perpendicular to the diffraction plane. New peculiarities of the rocking curves are obtained. The peculiarities of both the effective absorption coefficient and rocking curves in thick crystals are also investigated.

scholarly journals Synthesis and Characterisation of Thin Films of Bismuth Triiodide for Semiconductor Radiation Detectors

2014 ◽  
Vol 2014 ◽  
pp. 1-3 ◽  
Author(s):  
Alka Garg ◽  
Monika Tomar ◽  
Vinay Gupta
Keyword(s):  
Thin Films ◽  
Absorption Coefficient ◽  
Room Temperature ◽  
Active Material ◽  
Visible Region ◽  
Radiation Detectors ◽  
Radiation Absorption ◽  
X Rays ◽  
X Ray ◽  
Bismuth Iodide

Bismuth iodide is a potentially active material for room temperature radiation detector, as it is well reported in the literature that it has both wide energy band gap and high atomic absorption coefficient. Crystalline films of high atomic number and high radiation absorption coefficient can absorb the X-rays and convert them directly into electrical charges which can be read by imaging devices. Therefore, it was proposed to grow thin films of Bismuth iodide on glass substrate using thermal evaporation technique in vacuum to avoid the inclusion of impurities in the films. The structural studies of the films were carried out using XRD and optical absorption measurement was carried out in the UV/VIS region using spectrophotometer. All Bismuth iodide films grown at room temperature are polycrystalline and show X-ray diffraction peaks at angles reported in research papers. The optical transmission spectra of BiI3 films show a high transmission of about 80% in visible region with a sharp fall near the fundamental absorption at 650 nm. Resistivity of the as-grown film was found to be around 1012 ohm-cm suitable value for X-ray detection application. Films were subjected to scanning electron microscopy to study the growth features of both as-grown and annealed films.

Information Content of AVHRR Channels 4 and 5 with Respect to the Effective Radius of Cirrus Cloud Particles

1991 ◽  
Vol 30 (7) ◽  
pp. 973-984 ◽  
Author(s):  
F. Parol ◽  
J. C. Buriez ◽  
G. Brogniez ◽  
Y. Fouquart
Keyword(s):  
Absorption Coefficient ◽  
Mean Value ◽  
Effective Radius ◽  
Forward Peak ◽  
Effective Absorption Coefficient ◽  
Brightness Temperatures ◽  
Microphysical Properties ◽  
Effective Absorption ◽  
Cloud Particles ◽  
The Relationship

Abstract This paper investigates the important difference in the relationship between brightness temperatures between the 11-μm and the 12-μn AVHRR data and the microphysical properties of the semitransparent cirrus clouds. In the nonscattering approximation, the emittance for channels 4 and 5 are related through the absorption coefficient ratio that is the key parameter giving access to the size of cloud particles. The observed mean value of this parameter corresponds to effective radius of 18 μm for polydisperse spheres and 12 μm for polydisperse infinitely long ice cylinders. Taking the multiple scattering into account, the brightness temperature difference enhances much more for cylinders than for spheres owing to the fact that the forward peak of scattering is less large for cylinders. To obtain the size of cloud particles, the method developed in the nonscattering case is still applicable if one makes use of the effective emittance that implicitly includes the effects of mattering. Thus, an effective absorption coefficient ratio is defined and we derive a direct relationship between this ratio and the optical properties of the cloud particles. The mean value of the effective absorption coefficient ratio corresponds to ice spheres of effective radius of 26 μm or a bit less in the case of water spheres (supercooled droplets), but no agreement can be obtained for fully randomly oriented cylinders.

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.

An Improved X-Ray Fluorescence Method for the Analysis of Museum Objects

1969 ◽  
Vol 13 ◽  
pp. 94-104
Author(s):  
Maurice E. Salmon
Keyword(s):  
Critical Thickness ◽  
Alloy Composition ◽  
Fluorescence Analysis ◽  
Small Samples ◽  
Effective Absorption Coefficient ◽  
X Ray ◽  
Effective Absorption ◽  
Characteristic Wavelength ◽  
Museum Objects ◽  
Quantitative Results

A method is described for the x-ray fluorescence analysis of small samples, taken from museum objects, to determine alloy composition. The samples are dissolved in an appropriate reagent and absorbed on cellulose powder. The resulting powder is formed into a film of less than critical thickness and the effective absorption of the sample for the characteristic wavelength of the element being measured is determined. The effective absorption coefficient is used to correct the observed intensities in order to obtain quantitative results.

Effect of Compton Scattering on the Borrmann Effect of X-Rays in Silicon Crystals

1973 ◽  
Vol 28 (8) ◽  
pp. 1360-1365
Author(s):  
M. D. Giardina ◽  
A. Merlini
Keyword(s):  
Absorption Coefficient ◽  
Compton Scattering ◽  
Liquid Nitrogen ◽  
Dynamical Theory ◽  
Crystal Thickness ◽  
X Rays ◽  
Effective Absorption Coefficient ◽  
Silicon Crystals ◽  
Experimental Values ◽  
Integrated Intensities

The absolute integrated intensities diffracted in anomalous transmission through thick, nearly perfect crystals of silicon were measured for AgKα and MoKα wavelengths and for the {220} reflection, at room and liquid nitrogen temperatures. There is good agreement between experimental values and those calculated by using the formulas of the dynamical theory of diffraction, provided the contribution of Compton scattering μC* is included in the effective absorption coefficient μ*. μC* is a considerable fraction of μ* (from 23 to 55 per cent) for the two wavelengths and temperatures used in the present work. The experimental values of μC* agree well with those calculated by using the theory of the Compton contribution to the dynamical absorption coefficient of X-rays. A simple formula which is a good approximation of the rigorous expression of μC* is also given. The Debye temperature Θ of Si was derived from the experimental dependence of the intensities on crystal thickness for the {220} reflection at room and liquid nitrogen temperatures by using CuKα radiation. It was found that Θ = 521+5 and 543 + 5 °K at 295 and 77 °K, respectively, in agreement with the results of other authors.

Determination of the effective absorption coefficient for light in long plastic scintillators

1965 ◽  
Vol 2 (4) ◽  
pp. 242-244
Author(s):  
Yu. A. Tsirlin ◽  
A. R. Daich ◽  
T. I. Sokolovskaya ◽  
L. L. Nagornaya
Keyword(s):  
Absorption Coefficient ◽  
Effective Absorption Coefficient ◽  
Effective Absorption ◽  
Plastic Scintillators
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