POINT-DEFECTS IN DISORDERED SOLIDS - DIFFERENCES IN STRUCTURE AND REACTIVITY OF THE (SI-O)(2)SI - GROUPS ON SILICA SURFACE

The paper presents the results of studies of spectra and reactivity of intrinsic defects of silica including two-coordinated silicon atoms ( (=Si-O-)(2)Si:, silylene centers, SCs). Such centers, stabilized on th e surface of activated silica, are shown to differ in optical (absorpt ion and luminescent) spectra and effects in various chemical processes . These effects are quantitatively analyzed. Possible differences in t he SC geometry, resulting in the observed effects, are discussed using the quantum chemical calculations of molecular models. (C) 1998 Elsev ier Science B.V. All rights reserved.