Angle resolved X-ray photoelectron spectra study on surface state of uranium

The angle resolved X-ray photoelectron spectra (ARXPS) were used to study the initial oxidation process. In the study, the U4f, O1s and valence band XPS peaks of depleted uranium were obtained. The results indicate that ARXPS technique can be used to study the initial oxidation process of metallic uranium in more details. In present study it is found that the valence electron of uranium surface exhibits just delocalized state, and no localized state. Discussions were given compared with the results from literatures about the system 'U/substrate'. From comparison of the intensity ratio change with time of O1s and U4f XPS peaks acquired under 15 degree, 45 degree and 90 degree an apparent difference was observed, which shows that ARXPS is suited to study the initial oxidation process of uranium in the ultra high vacuum. (authors)