Low Energy X-Ray and Electron Absorption Within Solids (100-1500 ev Region)

Abstract

Quantitative analysis by x-ray fluorescence and photoelectron and Auger electron analysis can be effectively extended through a precise knowledge of the total aad subshell photoionization cross sections. Light element and intermediate element analysis, as based upon K and L series fluorescence respectively, involve x-ray interactions in the low energy region, Optimized analysis for essentially all the elements by x-ray induced photoelectron and Auger electron spectroscopy involves both x-ray and electron interactions in the low energy region. Unfortunately, theory and measurement for interaction cross sections in this 100-1500 eV region are difficult, particularly for the heavier elements. Nevertheless, recent advances in experimental and computerized-theoretical techniques for the determination of low energy interaction coefficients do permit establishing appreciatly more complete tabulations of cross sections than are currently available in this energy region.In this paper, the types of interaction cross section data that are needed for quantitative x-ray and electron analysis are defined. Such data that are available from experiment and from theory are reviewed and compared. Some newer techniques for the measurement of cross sections are discussed. And finally, new “state of the art” tables are presented for the mass absorption coefficients of all of the elements and of some special laboratory materials. These are tabulated specifically for twenty-six of the most commonly applied characteristic wavelengths in the 8-110 A region and are based upon the best currently available theoretical and experimental data.

Quantitative electron probe microanalysis of ultralight elements (boron‐oxygen)

“…The reason for this is quite simple: the vicinity of the MS edge in these elements produces a strong and nonlinear variation of MAC with wavelength, which makes inter-and extrapolation very dangerous. In many cases the new values we propose are somewhere intermediate between the older values of Henke and Ebisu (1974) and the more recent ones of Henke et al (1982); quite frequently, however, the older values seem to be better. As soon as an absorption edge is passed, the evaluation process has to start anew.…”

Uranium Soft X-Ray total Attenuation Coefficients

“…Log ;. versus loci E linear and quadratic regression fits to 3 n'easuremen?s of uranium Attenuation coefficients, r.. (cm /a) compared with theory (3) and compilations(11,12),…”

A Monte Carlo code to simulate the effect of fast secondary electrons on κAB factors and spatial resolution in the TEM

“…Clearly, there is a significant advantage in working with small thicknesses in order to minimize the effect of FSE on k A B factors and the effect of absorption. In this context, the critical thickness, t,, necessary to prevent absorption, calculated using the Tixier &Philibert (1969) criterion andHenke &Ebisu (1974) mass absorption coefficients, is equal to 6 nm for a B-95 wtyo Fe alloy, at which about 4.7% of the X-rays would be generated by FSE. Since it would be difficult to prepare a foil thinner than 6 nm, the effect of FSE should be included in the calculation of k A B factors, and the effect of B concentration on k* at 100 keV will be significant since practical thickness values range from 50 to 100 nm.…”