Search

The analysis of spectral luminescence characteristics of disperse Si02 indicates the presence of two types of surface oxygen vacancies (O-VI and O-VII). Their concentrations can be decreased by means of near UV and IR laser irradiation. It is established that the O-V concentration decreasing under IR irradiation (λirr = 1064 nm) in air is caused by their laser annealing under seven-photon ionization of surface O-V with the participation of atomic oxygen formed near the surface under dissociation of atmospheric 02 molecules in the laser field. The irradiation by near UV laser light (λirr ~250-360 nm) leads to a lower effective O-V concentration with decreasing IR irradiation. The analysis of the dose dependence shows that in this case the observed effect is due to the interaction of surface O-V with bulk reagents (water, OH− groups, 02 centers) or their photolysis products, not with atmospheric oxygen. The choice of laser irradiation wavelength is important for selective effect on O-VI and O-VII c...