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- Author or Editor: S. J. Birstein x
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Abstract
Studies have been made of the adsorption of water vapor on photolyzed silver iodide. Adsorption isotherms, run at +20 and −20C, have been compared with the isotherms of water vapor on unphotolyzed silver iodide at the same temperatures. It has been found that, while water on silver iodide gives a type III isotherm characterized by extremely high multilayer adsorption, as the silver iodide is photolyzed and its nucleating ability destroyed, water adsorption is greatly diminished.
Abstract
Studies have been made of the adsorption of water vapor on photolyzed silver iodide. Adsorption isotherms, run at +20 and −20C, have been compared with the isotherms of water vapor on unphotolyzed silver iodide at the same temperatures. It has been found that, while water on silver iodide gives a type III isotherm characterized by extremely high multilayer adsorption, as the silver iodide is photolyzed and its nucleating ability destroyed, water adsorption is greatly diminished.
The effect of adsorbed water vapor on the photolysis of silver iodide has been studied. Inn has found that when silver iodide nuclei are exposed to ultraviolet light before injection into a cold chamber containing a cloud of supercooled water droplets, no ice formation is observed. Reynolds, Hume, Vonnegut and Schaefer have investigated the effect of bright sunlight on the action of silver iodide as a sublimation nucleus, and have found a decrease in the magnitude of nucleating effectiveness which is less than that observed by Inn.
The studies in this laboratory have been concerned with the effect of relative humidity on the photolysis and subsequent nucleating properties of silver iodide particles. Known amounts of water vapor were introduced into a stream of nitrogen passing over a silver iodide generator. The silver iodide particles, covered with adsorbed water, were collected in a cell and exposed to ultraviolet light of known intensity for varying amounts of time. After irradiation, the silver iodide particles were injected into a cloud of supercooled water droplets and ice formation was watched for. The nucleating effectiveness of silver iodide exposed to ultraviolet light was found to be directly dependent on the relative humidity of the gas stream passing over the generator.
The effect of adsorbed water vapor on the photolysis of silver iodide has been studied. Inn has found that when silver iodide nuclei are exposed to ultraviolet light before injection into a cold chamber containing a cloud of supercooled water droplets, no ice formation is observed. Reynolds, Hume, Vonnegut and Schaefer have investigated the effect of bright sunlight on the action of silver iodide as a sublimation nucleus, and have found a decrease in the magnitude of nucleating effectiveness which is less than that observed by Inn.
The studies in this laboratory have been concerned with the effect of relative humidity on the photolysis and subsequent nucleating properties of silver iodide particles. Known amounts of water vapor were introduced into a stream of nitrogen passing over a silver iodide generator. The silver iodide particles, covered with adsorbed water, were collected in a cell and exposed to ultraviolet light of known intensity for varying amounts of time. After irradiation, the silver iodide particles were injected into a cloud of supercooled water droplets and ice formation was watched for. The nucleating effectiveness of silver iodide exposed to ultraviolet light was found to be directly dependent on the relative humidity of the gas stream passing over the generator.
Abstract
A careful study has been made of the nucleating ability of various chemicals. The nuclei were prepared in a nitrogen atmosphere, rather than air, to prevent a reaction at the hot filament with atmospheric oxygen. With use of these carefully controlled conditions, numerous materials previously reported as effective were found to be poor nucleating agents. The discrepancies among the various sets of data were found to be due to reaction at the filament of the solid material and oxygen in previous investigations. The results are examined to determine how they support prevailing theories on ice-crystal formation.
Abstract
A careful study has been made of the nucleating ability of various chemicals. The nuclei were prepared in a nitrogen atmosphere, rather than air, to prevent a reaction at the hot filament with atmospheric oxygen. With use of these carefully controlled conditions, numerous materials previously reported as effective were found to be poor nucleating agents. The discrepancies among the various sets of data were found to be due to reaction at the filament of the solid material and oxygen in previous investigations. The results are examined to determine how they support prevailing theories on ice-crystal formation.
