A computer simulation of the interaction of unsaturated vapors with a defective surface of a β-AgI crystal

Based on computerized simulation data, it is found that a water monolayer is formed on the surface of a silver iodide crystal when the pressure of an unsaturated water vapor exceeds a certain value The layer exhibits an avalanche-like growth. The electric field of an extra ion pair at the crystal surface gives rise to the formation of spots composed of fragments of a two-dimensional network of water molecules linked via hydrogen bonds with a pattern repeating the hexagonal structure of the crystal surface. Such spots in the dipole's field are thermodynamically stable and form at a vapor pressure below a threshold value. The diameter of each spot increases with the vapor pressure. At the threshold vapor pressure, the spots merge to cover completely the surface of the crystal