GEMINAL SILANOL GROUPS AT THE SURFACE OF SILICA

The process of oxidation and successive hydrogenation of the surface of ''reactive silica'' are studied by W-VIS and FT-IR spectroscopy. Geminal silanol groups were found to be the major hydrogenation products. The frequencies of the O-H stretching vibrations were measured for these groups, which contained different isotopes (O-16, O-18, H, D). At temperatures above 1000 K, the decomposition of silanediol groups occurs with the formation of terminal silanol groups. The integral extinction coefficients for silylene [(=Si-O-)(2)Si:, 238 nm], silanediol [(=Si-O-)(2)Si drop(O-D)(O-D), 2762.0 cm(-1)], silanol and silylhydride fragments [(=Si-O-)(2)Si drop(O-H)(H), 3741 and 2270 cm(-1)] were determined.