Structural changes induced by KrF excimer laser photons in H-2-loaded Ge-doped SiO2 glass

Photochemical reactions related to the Ge lone-pair center (GLPC) that an i nduced by KrF excimer laser photons in H-2-loaded Ge-doped SiO2 glass have been investigated. Without the H-2 loading, the Ge electron center (GEC) an d the positively charged GLPC were induced by the laser irradiation. In the H-2-loaded sample, the GEC, the Ge E' center, and the germyl radical (GR) were induced by the irradiation, while the positively charged GLPC was not observed after the irradiation. If the H-2-loaded sample was thermally anne aled after the photon irradiation, the concentration of the photo-induced G EC decreased monotonically with an increase in the annealing temperature. O n the other hand, the concentration of the GR increased up to the annealing temperature of 160 degrees C, and it decreased at higher temperatures. Wit hout the pre-irradiation, the induction of the GR was not observed even in the H-2-loaded sample. From these results, it is concluded that the positiv ely charged GLPC is terminated with a hydrogen atom in the H-2-loaded sampl e and then becomes the GR by trapping an electron thermally released from t he GEC. [S0163-1829(99)05631-3].