Growth and properties of particulate Fe films vapor deposited in UHV on planar alumina substrates

Abstract

An integrated experimental approach was used to prepare and characterize well-defined particulate deposits of Fe on a variety of planar Al2O3 supports. The Fe particles were vapor deposited in UHV on in-situ cleaned and characterized amorphous and single crystal alumina supports at controlled substrate temperatures and deposition rates. Integrated support and deposit properties were monitored in-situ by AES, XPS, and LEED; particle number densities and sizes were monitored by standard TEM. It was found that a) metal exposure is an insufficient and often misleading measure of particle size when the support surface properties are unknown or poorly controlled, b) judicious combination of depostion temperature and impingement flux lead to size- and number density-controlled particulate deposits of good thermal stability, which can be improved by annealing. Preliminary results of XPS and of CO-TPD and H2-TPD measurements exhibiting particle size effects are also reported. © 1986 Springer-Verlag.