INS and IR Studies of Intermolecular Interaction at the Silicone-Fumed Silica Interface. 3. Adsorption Complexes

Surface vibrations of a five-member polydimethylsiloxane oligomer Si5 adsorbed at different coverages on hydroxylated and silylated fumed silica have been studied by inelastic neutron scattering at low temperature and by DRIFT at room temperature. The changes in the AWDS spectra are recorded which might be attributed to immobilization of the adsorbed molecules on the surface, as well as to the pressure effect on the TMS units of substrate caused by adsorbed molecules. Assignment of the observed spectra is done on the basis of the solution of the direct and inverse spectral problems with the force field initially determined quantum-chemically.