A mechanism for photoinduced electronic reconstruction of the oxygen vacancy in doped quartz glass and its characteristics

A mechanism is proposed for electronic reconstruction of excited oxygen-def icient (OD) centers in doped quartz glass, associated with partial delocali zation of one of the valence electrons. Using Falicov's model Hamiltonian, the binding energy, radius, and criterion for an electron transition from a localized state to a state of intermediate radius are qualitatively determ ined. Densification of the glass matrix surrounding the OD centers is predi cted as a possible consequence of the reconstruction of their valence elect rons. An explanation is proposed for the irreversible photoinduced changes in refractive index, photoluminescence spectra, and electron paramagnetic r esonance that are experimentally observed in doped quartz glasses after pro cessing with large doses of ultraviolet light. (C) 1999 American Institute of Physics. [S1063-7834(99)01906-1].