Periodic Multilayer for X-ray Spectroscopy in the Li K Range

Abstract

X-ray spectroscopy of lithium is very difficult, even impossible, with wavelength dispersive spectrometers commonly deployed on scanning electron microscopes or electron microprobe analyzers. This is due to the absence of crystals and lack of efficient periodic multilayer for this spectral range, around 50 eV. To address this issue, we propose using a Be/Si/Al multilayer having a period of about 29 nm. The multilayer was deposited by magnetron sputtering and its reflectivity measured as a function of the glancing angle in the spectral range of the Li K emission and as a function of the incident energy up to ~200 eV. This characterization demonstrates that the designed multilayer is suitable to efficiently perform spectroscopy in the range of the Li K emission in terms of reflectance (0.32 at 51.5 eV), bandwidth (around 3.5 eV) and rejection of high order diffracted radiation.

Calculation of emission spectra of lithium compounds

“…The 0.5 eV Gaussian broadening is typical of the width of the diffraction pattern of a grating used to disperse X‐ray radiation. If a spectrometer equipped with a periodic multilayer would be used, then a Gaussian broadening of 2.5–3 eV would be expected 17 …”

“…For lithium fluoride, LiF, we have found only eight references [6][7][8][9][10][11][12][13], presenting large differences in shapes, width, and energy depending on: the excitation means, electrons or photons; the excitation conditions, electron energy, electron current, and duration of the excitation, … In these conditions, it would be valuable for the x-ray spectroscopist to consolidate his results by comparing his Li K spectra to those obtained from ab initio calculations. This is all the more important since the recent development of new spectrometers [14][15][16] and periodic multilayers 17 to be set up on scanning electron microscopes and electron probe microanalyzers to probe the ultra-soft x-ray range and particularly the Li K emission band around 50 eV.…”

High-accuracy experimental determination of photon mass attenuation coefficients of transition metals and lithium fluoride in the ultra-soft energy range

“…5 The authors warn of their use in the extreme low energy range without considering the uncertainties that can be of several hundreds of percent. 6 With the advances in analytical techniques in the low energy range, [7][8][9][10] emerging complex simulation methods, [11][12][13] and the steadily increasing demand for the characterization of strategic materials containing light elements, an exact determination of MACs of elements of interest in the extreme low energy range and around their absorption edges becomes necessary. Especially, the analysis of materials containing lithium, for example, lithium-ion batteries, is a current important issue.…”

Electron probe microanalysis of light elements: Improvements in the measurement and signal extraction methods

“…After the pioneer work of Castaing, Bastin et al focussed for the first time on the problems of EPMA of light elements in the late 1980s 1,2 and there has been great progress, especially in instrumentation and signal processing. The implementation of recently developed periodic multilayers in today's microanalysers allows spectroscopy of light elements, 3 even at extreme low energies in the Li K range 4 . Even though quantitative EPMA of light elements is possible in theory, there are many difficulties to overcome.…”

“…The implementation of recently developed periodic multilayers in today's microanalysers allows spectroscopy of light elements, 3 even at extreme low energies in the Li K range. 4 Even though quantitative EPMA of light elements is possible in theory, there are many difficulties to overcome.…”