Photolytic Inactivation of Ice-Forming Silver Iodide Nuclei

Abstract

Photolytic decomposition of silver-iodide crystals has been observed when the crystals were exposed to light of wave lengths less than 4300Å, as indicated by darkening of the exposed crystals. Qualitative observations indicate exposed silver iodide crystals undergo reversible photolysis, although the exact conditions under which this takes place is not well understood. When silver iodide nuclei were similarly exposed to light, the ability to form ice particles, when injected into a cloud of super-cooled water droplets, was found to be essentially destroyed. It is believed that, as a result of photolysis of the exposed silver iodide nuclei, the physico-chemical nature of surface of the nuclei has been altered to minimize effectively the surface-structure sensitive process of ice nucleation.