Infra-red study of the adsorption of ammonia on MgO. Part 1.—The dehydrated surface

Abstract

The adsorption of ammonia gas has been studied on dehydrated MgO. The symmetrical bending vibration ν₂ of ammonia is considerably perturbed by the presence of the surface and a doubling of this band is observed at low concentrations of ammonia. Models for the nature of the adsorbed species are discussed and it is concluded that the ammonia molecule is probably hydrogen-bonded to an oxide ion in the surface. There is no evidence for Brønsted or Lewis acid sites on the surface.