A Metal Cluster Generator for Gas Phase Electron Diffraction and Its Application to Bismuth,Lead and Indium:Variation in Microcrystal Structure with Size.

摘要

The objective of the work presented here is to determine the differences in structure of small metal microcrystals from that of the bulk phase as the average size is diminished. The size at which changes occur, as well as the nature of these changes, is of importance. The metal is vaporized in an oven in the presence of argon, an inert or carrier gas which initiates the metal nucleation and growth in the gas phase, near the evaporating surface. The newly formed microcrystals or clusters are entrained into a subsonic free jet and transported through a double orifice sampling arrangement. The portion of the argon-metal cluster mixture that passes through the second orifice or nozzle expands as a supersonic free jet and is crossed by a 40 kev electron beam 1 to 2 nozzle diameters downstream where diffraction patterns are taken on glass photographic plates.