U.S.-Germany Cooperative Research on the Homogeneous Nucleation of Metal Vapors

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This award supports Joseph L. Katz of Johns Hopkins University for collaborative research in chemical engineering with Professor Friedrich Hensel of Phillips University in Marburg, Germany. They are cooperating in a study that involves the use of upward thermal diffusion chambers to measure the homogeneous nucleation of cesium and other metal vapors. Their research plan exploits the complementary strengths of the two research groups. The German group led by Dr. Hensel is well known for their research on the metal-insulator transition and other properties of metal vapors. They have state-of-the-art facilities where they are actively studying supersaturated mercury vapor. Dr. Katz and his group are expert in the use of the diffusion cloud chamber and in nucleation theory. They have a very active program using upward thermal diffusion cloud chambers for the study of homogeneous and other nucleations. Most of the experimental work will be done in Marburg, with some data analysis and other support going on in Maryland. Reciprocal visits of members of the two research groups will facilitate this joint work. Nucleation processes are extremely widespread in the natural world as well as in the laboratory. However, our ability to predict the conditions that cause nucleation and the rate at which it occurs in typical processes is almost non-existent. Homogeneous nucleation of a liquid from its supersaturated vapor is particularly amenable to theoretical and experimental study. The nucleation properties of metals are quite different from those of non-metals, and they are of growing importance as technologies develop to produce and use novel alloys or to use known metals in novel ways.