Chemical state analysis of tungsten and tungsten oxides using an electron probe microanalyzer

In this research, the discrimination of tungsten and different oxidization states of its oxide has been studied using an electron probe microanalyzer (EPMA), and the results have been compared with those obtained by X-ray photoelectron spectroscopy (XPS). As a result, the relationship between the oxidization state of tungsten oxide and the intensity ratio of W Mbeta/Malpha in the X-ray spectra of EPMA has been clarified in small-area analysis. We can discriminate W, WO2, W18O49 (WO2.72) and WO3 using EPMA under given conditions. Comparing XPS with EPMA, a practical disadvantage of XPS is that the small-area analysis is sometimes difficult using the conventional XPS equipment, while the commercially available EPMA easily achieves a few micrometer resolution. XPS measurement is sensitive in the surface state; EPMA can be used to measure without being influenced by surface oxidation.