Radiation damage studies by x-ray photoelectron spectroscopy. I. Electron irradiated LiNO3 and Li2SO4

Abstract

X-ray photoelectron spectroscopy (XPS) was applied to the study of radiation damage on the surfaces of LiNO3 and Li2SO4 single crystals which were free of carbon contamination. Irradiations were done in situ at room temperature with 0.3–1.6 keV electrons. The products, assigned from chemical shifts in the binding energies of core levels, were: LiNO2 and Li2O from irradiated LiNO3 and Li2SO3, elemental sulfur, Li2S, Li2O, and adsorbed oxygen species from irradiated Li2SO4, respectively. There was no indication in either sample of the metallic lithium formation reported previously. Heavy irradiations of the Li2SO4 sample showed that the final products of the radiation decomposition are Li2O and Li2S. The G values (the number of molecules produced or decomposed per 100 eV of radiation absorbed) of the radiation decomposition and product formation for 1.4 keV incident electrons were estimated from differential energy loss to be approximately 10−3–10−4.