The development of X-ray photo-emission electron microscopy (XPEEM) for valence-state imaging of mineral intergrowths

摘要

We demonstrate the potential of X-ray photo-emission electron microscopy (XPEEM) to reveal valence-state images of the spatial distribution and relative concentration of metals in specific oxidation states. Additionally, XPEEM allows X-ray absorption spectra to be extracted from chosen pixel areas of the images. Using an in-house-built XPEEM instrument we show an application of the method in providing valence-state images of complex mineral intergrowths. The image resolution achieved with this instrument of simple design was approx 5 mu m and reasonable quality X-ray absoiption spectra were extracted from areas of approx 5 X 5 mu m. These initial results suggest that by using commercial XPEEM instruments on 3~(rd) generation, high-brightness synchrotron sources a spatial resolution of 100 nm or better could be achieved, with the ability to extract high-quality X-ray absorption spectra from areas of 0.1 mu m~2. Given that standard thin sections or polished blocks can be studied by XPEEM, and that each XPEEM image records approx 1000 mu m~2, XPEEM can be used in conjunction with other analytical methods such as EMPA and TEM-EELS/PEELS.