Formation of the transition layer at the vapor-crystal interface

Abstract

INTRODUCTIONIntense studies of the interactions between aerosolsand atmospheric moisture have been ongoing for sev-eral decades now. A significant amount of experimentalmaterial has been accumulated, but a satisfactory expla-nation of the mechanism that determines the strong dif-ferences in the activity of various reagents has not yetbeen found. Among known reagents, the most active issilver iodide. The hexagonal crystalline lattice of thebeta modification of AgI may be the simplest naturalexplanation for the high activity of this substance, as itpossesses a crystalline order that is close to the molec-ular order of ice. However, this explanation is inconsis-tent with the moderate wettability of the single-crystalAgI surface. Silver iodide acquires its unique propertiesfollowing an intense thermal and mechanical treatmentin which it is transformed into the aerosol state. Weshould, first of all, associate this effect with the forma-tion of crystalline defects on the particle’s surface in theprocess of preparing aerosol.These crystalline defects manifest themselves byblocking the surface adsorbability due to their smalladmixtures in the atmosphere. In [1], the action ofammonia on the activity of silver iodide and lead iodidewas studied, the essential suppression of both iodideactivities having been observed. The deactivatingaction of gases can then be explained by chemisorptionand the blockage of active centers on the surface of ice-forming particles. In natural experiments, the loweringice-forming-aerosol activity in the vicinity of chemicalplants was observed. An analogous experimental inves-tigation [2] has revealed the significant effect of indus-trial-gas admixtures on the ice-forming activity of sil-ver iodide. In [3], the strong effect of volume chemicaladmixtures in silver iodide crystals on their ice-formingproperties was found. The AgI—NH