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

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 similar to5 mum, and reasonable quality X-ray absorption spectra were extracted from areas of similar to5 x 5 mum. These initial results suggest that by using commercial XPEEM instruments on 3(rd) generation. high-brightness, synchrotron sources a spatial resolution of 100 urn or better could be achieved, with the ability to extract high-quality X-ray absorption spectra from areas of 0.1 mum(2). Given that standard thin sections or polished blocks can be studied by XPEEM. and that each XPEEM image records similar to1000 mum(2), XPEEM can be used in conjunction with other analytical methods such as EMPA and TEM-EELS/PEELS