Hydrogen bond surface chemistry: Interaction of NH3 with an ice particle

The study focuses on interaction of a "strong" adsorbate with an ice surfac e. Ammonia adsorption on an ice cluster (H2O)(293) is investigated by Monte Carlo simulations, as a function of coverage at T = 110 K. At low coverage s, ammonia is attached to dangling H-atoms on the surface, while forming ad ditional weaker bonds with neighboring dangling O. At high coverages insert ion is observed of the NH3 molecules into the surface. The process is drive n by the ability of NH3 molecules to cleave strained H2O ... H2O hydrogen b onds in the ice surface, and to form strong N ... HO bonds with the water m olecules.