UV photon and low-energy (5-150 eV) electron-stimulated processes at environmental interfaces

Summary form only given. Irradiation of surfaces and interfaces with low-energy (5-150 eV) electrons and ultraviolet photons occurs during the storage of "mixed" (chemical/radioactive) waste forms and during processing steps which involve the use of low temperature plasmas. It is well known that electron- and photon-stimulated desorption (ESD and PSD) from wide band-gap materials and interfaces can be initiated by Auger decay of deep valence and shallow core holes. We present results on the ESD and PSD of environmentally relevant substrates such as ZrO/sub 2/(100), soda-glass, and NaNO/sub 3/. The major cation thresholds and yields indicate that ESD and PSD from these complex materials involves Auger stimulated events. In particular, desorption thresholds correlate with ionization of the O(2s), Zr(4p), Si(2p) and Na(2s) levels. The near band-gap threshold energy (/spl sim/5-7 eV) for the desorption of neutrals (i.e., atomic oxygen, NO, etc.) demonstrate the overall importance of self-trapped and localized excitons in both ESD and PSD of typical ceramics and oxides.