SSIMS AND XPS STUDIES OF RECONSTRUCTION OF ALUMINA-SUPPORTED RH PARTICLES

Rhodium particles were vapor-deposited on (-1012) alpha-alumina and po lycrystalline gamma-alumina substrates. Variations of morphological pa rameters during the growth and/or thermal annealing in vacuum, oxygen and CO atmosphere have been investigated by means of static SIMS and X PS, The ratios of Rh/substrate ion species and the Rh 3d electron bind ing energy variations indicated changes in metal coverage given by par ticle size and dispersion variations. The heating of as-deposited part icles in vacuum led to the particle coalescence. On the other hand the oxygen interactions with particles gave an increase of particle dispe rsion.