Journal of X-Ray Science and Technology - Volume 8, issue 4

Authors: Schneider, S. | Bazin, D. | Dubuisson, J.M. | Ribbens, M. | Sonneville, H. | Meunier, G. | Garin, F. | Maire, G. | Dexpert, H.

Article Type: Research Article

Abstract: This paper presents a new in situ X-ray reaction cell dedicated to in situ X-ray absorption studies of postcombustion catalytic converter. This device has been developed to collect Exafs spectra during the chemical reactions, the sample being placed under the flow of a complex mixture of reactive gases (NO, CO, N2 ,...). Particular attention has been paid to the material and the design of the sample holder. More precisely, a specific geometry of the sample holder …has been elaborated in order to study directly the catalyst as it is in the converter. Also, we have tried here to respect the particular reaction conditions namely high temperature and high space velocity associated to postcombustion. Show more

Keywords: New experimental device, furnace, in situ X-ray absorption spectroscopy, fluorescence mode, automotive postcombustion, catalytic converter

Citation: Journal of X-Ray Science and Technology, vol. 8, no. 4, pp. 221-230, 1998

Authors: Sailaja, S. | Naik, P.A. | Arora, V. | Gupta, P.D.

Article Type: Research Article

Abstract: Effect of distortion in free-standing gold microstructure transmission gratings resulting in appearance of half integral orders in X-ray spectra is reported. XUV-soft X-ray spectra of moderate Z plasmas produced by 2GW, 4 ns/28 ns (FWHM), Nd: glass laser pulses showed low intensity peaks corresponding to half integral orders (up to m=7/2), in addition to the normal diffraction orders. These are explained to occur due to a symmetric distortion in the part of grating …structure used, which leads to a periodicity in twice the grating period. Experimentally measured intensity ratios of different diffraction orders are consistent with the theoretical values calculated for the grating structure observed under a scanning electron microscope. This distortion, however, does not affect the spectral resolution of 0.6Å (in the first order) as expected and measured for the undistorted part of the grating structure. Show more

Citation: Journal of X-Ray Science and Technology, vol. 8, no. 4, pp. 231-239, 1998

Authors: Giakos, G.C. | Vedantham, S. | Suryanarayanan, S. | Chowdhury, S. | Odogba, J. | Dasgupta, A. | Guntupalli, R. | Sha, N. | Vega-Lozada, V. | Sumrain, S. | Mehta, K. | Patnekar, N.

Article Type: Research Article

Abstract: In this study, the temporal response of a planar Cd1-x Znx Te sample at each frequency of a scanning square-wave test pattern, has been measured. The experimental setup offers potential capabilities for feasibility studies, research, and evaluation of the temporal response and noise characteristics of a Cd1-x Znx Te X-ray sensor system, for fast digital radiographic applications. The dependence of the temporal response of the experimental X-ray detector system on physical and …geometrical parameters has been determined experimentally. The results of this study indicate that the overall temporal response of the Cd1-x Znx Te detector system improves with increasing applied electric field, and scanning speed, as well as decreasing detector thickness, and object magnification. Further improvements of the geometrical and signal collection parameters of the detector will improve the speed of the X-ray system significantly. Show more

Citation: Journal of X-Ray Science and Technology, vol. 8, no. 4, pp. 241-251, 1998

Authors: Kozhevnikov, Igor V. | Pyatakhin, Mikhail V.

Article Type: Research Article

Abstract: The formulas for X-ray scattering diagram are deduced and analysed in the first order Distorted Wave Born Approximation (DWBA) without any simplified assumption about an unperturbed wave field nearby a~rough interface. The comparison with other approaches described in literature is given. The possibilities of DWBA and the perturbation theory (PT) are discussed as applied to development of X-ray method of the surface roughness control. It is shown that just PT is the most natural and correct …theoretical basis of X-ray testing method which permits one, in contrast to DWBA, to extract information from the scattering measurements by unambiguous manner. It is demonstrated that there is the optimum radiation wavelength lying in the soft X-ray and EUV spectral regions which provides a~means for an extraction of the maximum amount of information about the surface microtopography from the scattering measurements. Application of existing EUV lasers for the study of the surface roughness is discussed. Show more

Citation: Journal of X-Ray Science and Technology, vol. 8, no. 4, pp. 253-275, 1998

Authors: Rantamäki, R. | Tuomi, T. | Zytkiewicz, Z.R. | McNally, P.J. | Danilewsky, A.N.

Article Type: Research Article

Abstract: Synchrotron X-ray topographs of epitaxial laterally overgrown GaAs (ELO) samples are made in both transmission and reflection geometries. Samples grown on GaAs substrates with separated and merged ELO layers are studied. Transmission, transmission section, back-reflection, back reflection section and grazing incidence X-ray topographs are compared. The topographs, complementary to each other, show that the bending of the ELO layers is visible in all geometries, though ELO images are seen in different ways in different …geometries. The observed contrast of the ELO layers is explained using a model based on orientational image contrast. A pair of back-reflection section and back-reflection topographs taken subsequently from the same position is required for successful and unambigious interpretation of topographs. Show more

Citation: Journal of X-Ray Science and Technology, vol. 8, no. 4, pp. 277-288, 1998