RAMAN-SCATTERING FROM AMMONIA ADSORBED ON THE AMORPHOUS SILICA SURFACE

We have performed measurements of the perturbations of the Raman spectrum of ammonia molecules due to adsorption on the surface of porous Vycor glass. The spectrum of hydrogen bonded NH3 is studied as a function of coverage and related to changes in the substrate surface phonon spectrum. More strongly chemisorbed ammonia species are also observed. When NH3 is adsorbed on a partially deuterated surface we observe a slow chemical reaction in which the adsorbed NH3 exchanges hydrogen with a surface deuteroxyl group: we observe in addition to the changes due to NH3 interacting with OH groups the appearance of adsorbed NH2D and the near complete replacement of surface OD with OH. © 1979 American Institute of Physics.