Abstract
ESR absorption of adsorbed oxygen on zine oxide were .measured at 77∼210°K in vacuum to inverstigate the absorbed species of oxygen. The results are as follows:
(1) ESR spectra of adsorbed oxygen on zine oxide at g=2.003∼4, g=2.014, g≒2.04 and g≒2.06 are detected at 77°K in vacuum. Here, g is the spectroscopic factor of ESR absorption.
(2) All of the relative intensities of ESR spectra are decreased with incresing temperature at 77∼210°K. Above all, the spectrum at g=2.014 is disappeared at 100∼106°K. These will mean that the adsorbed oxygen on zinc oxide is desorbed.
(3) At 77°K, all of the relative intensities of ESR spectra are decreased by UV-irradiation. These are caused by photo-desorption of the absorbed oxygen on zinc oxide. And also, since the relative intensities are gradually increased after UV -irradiation, the adsorption of oxygen on zinc oxide is reversible.
(4) The ESR spectrum at g=2.003∼4 is due to an O- (ads) -type oxygen that is formed by the following process: 1/2 O2 (g) +Θ→O- (ads). Here, the symbol, Θ indicates an electron in the conduction band of zinc oxide.
(5) The ESR spectrum at g=2.014 will be due to an ozonide-type oxygen, O3- (ads), since the value is nearly equal to the g-value of ESR spectrum observed in NaO3 (g∥=2. 003, g⊥=2. 015).
