Viberational spectroscopy of dispersed silica: inelastic neutron scattering

The results of a large inelastic neutron scattering (INS) experiment performed for different kinds of the dispersed silicas are presented. The amplitude weighted density of states (AWDS) spectra are obtained from the INS spectra recorded at 10, 80 and 290 K. The two aerosil samples differing twice in specific areas (A380 and A175) as well as the two silica gels with the pore size of 20 and 100 Å (SG20 and SG100) are studied. The results obtained for the "A380-family" of samples consisting of aerosil A380 equilibrated with light and heavy water at relative humidity of 60-70%, dried at 700°C and sintered at 1200°C allowed to separate their AWDS spectra into the siloxan core spectra and spectra of the OH + H2O, H2O and OH shells. These sorts of spectra are got for the silica gels. The AWDS spectra for the aerosils and the silica gels are quite different indicating a big difference in the structure of cores and shells of both the silicas as well as in the water molecule arranging on them. The possibility to tackle the results in terms of the computation chemistry is discussed. © 1990.