Hard X-ray photoemission spectroscopy

Shikano M., Kobayashi H., Koike S., Sakaebe H., Ikenaga E., Kobayashi K, Tatsumi K Investigation of positive electrodes after cycle testing of high-power Li-ion battery cells II An approach to the power fading mechanism using hard X-ray photoemission spectroscopy, J. Power Sources 2007, 174,795-799. 

During the last 5 to 10 years there has been much interest in electron spectroscopies (Hiifner and Steiner 1982), since it was realized that these also suggest a very different picture of mixed valence Ce compounds. Valence photoemission spectroscopy (PES) studies showed that the f-spectrum of Ce has weight at (8p ) — 2eV below Ep (Platau and Karlsson 1978, Johansson et al. 1978). It was further found that core level X-ray photoemission spectroscopy (XPS) measurements were hard to understand unless A (Fuggle et al. 1980b) is much larger than previously assumed. This discrepancy between the interpretations of spectroscopic and thermodynamic data showed the need for a theoretical analysis, based on a microscopic model, of what kind of information can be extracted from different experiments. This was further emphasized when PES studies showed f-character in the spectrum both at —2eV and close to 8p = 0 (Martensson et al. 1982). This observation created a lively debate about how to interpret the PES spectra. 

With the availability of intense tunable radiation in the range firom ultraviolet to hard X-rays from synchrotrons, powerful new experimental techniques have been developed to probe the structural and electronic properties of solids and surfaces. In particular, angle-resolved photoemission gives information about the electronic properties in the valence bands of solids while core level spectroscopy provides an element-specific spectroscopic tool. 

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