Measurements are made in ultra-high vacuum of the effectiveness of photodesorption, Φ, of oxygen with hν<3.2 eV and of the changes in band inclination, ΔVs, of zinc oxide within the 300<T<500 K temperature range. The Φ(T) function is seen to exhibit two maxima at T≈380 and ≈470 K replicating the oxygen thermodesorption spectrum, and ΔVs(T) is shown to correlate with them. A model is proposed that treats photodesorption as a multistage process. The first stage consists in the photodischarge of surface states of non-adsorbent origin followed by electron transfer from the absorbed oxygen to the vacated state. The discharged oxygen passes over to a predesorption state from which it is eventually desorbed. The temperature behavior of Φ is determined by a greater band inclination caused by electron transfer to surface states from the absorbed oxygen in the course of its desorption.
|Журнал||Soviet journal of chemical physics|
|Состояние||Опубликовано - 1 дек 1992|
Предметные области Scopus
- Технология (все)