Role of diffusing molecular hydrogen on relaxation processes in Ge-doped glass

Temperature dependencies of steady-state and time-resolved photoluminescence (PL) from triplet state at 3.1 eV and singlet state at 4.2 eV ascribed to the twofold-coordinated Ge have been measured in unloaded and H2-loaded Ge-doped silica samples under 5.0 eV excitation in the 10–310 K range. Experimental evidences indicate that diffusing molecular hydrogen (H2) depopulates by a collisional mechanism the triplet state, decreasing both its lifetime of about 14% and the associated triplet PL intensity, whereas those of the singlet are insensitive to the presence of H2.