Condensation Kinetics of Iron and Silicon in the Vapor Phase,
STUTTGART UNIV (GERMANY F R) INST FUER PHYSIKALISCHE CHEMIE
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Atomic vapors of iron or silicon were generated by shock heating the compounds FeCO5 or SiH4 in the incident concentrations of the compounds in argon in the driven section of the tube drive gas He were sufficiently low that ideal shock tube operation and an isothermal condensation reaction can be assumed. Varying shock wave temperature and initial compound concentration we produced supersaturated states between incident and reflected shock wave. The atomic vapors condensed to form small clusters of the two elements. The rate of formation of these droplets was detected using atomic and molecular spectroscopy and light scattering respectively. Because of the surface tension looses its proper meaning for particles of atomic dimensions, classical nucleation theory cannot be used for comparison with the experiments. Therefore, condensation on the basis of a new hypothesis omitting the use of the surface tension was undertaken.