The diffusion and reactions of hydrogenous species generated by single-pulsed F2 laser photolysis of SiO-H bond in SiO2 glass were studied in situ between 10 and 330K. Experimental evidence indicated that atomic H (H0) became mobile even at temperatures as low as about 30K. A sizable number of H0 dimerized via a diffusion-limited reaction into H2; that could migrate above about 200K. The activation energies for diffusion, inherently scattered due to structural disorder in the glass, were separated into 3 bands that were centered at about 0.1eV for free H0, at about 0.2eV (presumably due to shallowly-trapped H0) and at about 0.4eV for H2.

Diffusion and Reactions of Hydrogen in F2-Laser-Irradiated SiO2 Glass. K.Kajihara, L.Skuja, M.Hirano, H.Hosono: Physical Review Letters, 2002, 89[13], 135507 (4pp)