Infra-red study of the adsorption of ammonia on MgO. Part 2.—The hydrated surface

Abstract

Ammonia is weakly adsorbed on hydrated MgO by hydrogen-bonding of the nitrogen to hydroxyl groups exposed on the surface a strong band at 3045 cm^–1 is attributed to surface hydroxyl groups perturbed by the adsorbed ammonia. A rapid isotopic exchange is evident when ND₃ is adsorbed; a band ascribed to the symmetric bending frequency is observed at 1137 cm^–1 for adsorbed NH₃, and two bands at 945 and 860 cm^–1 observed when ND₃ is adsorbed are assigned to NHD₂ and ND₃ respectively. All traces of ammonia can be removed by evacuation at room temperature.