| Numéro |
J. Phys. Colloques
Volume 47, Numéro C7, Novembre 1986
33rd International Field Emission Symposium / 33ème Symposium International d'Emission de Champ
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| Page(s) | C7-419 - C7-424 | |
| DOI | https://doi.org/10.1051/jphyscol:1986770 | |
J. Phys. Colloques 47 (1986) C7-419-C7-424
DOI: 10.1051/jphyscol:1986770
TEMPERATURE DEPENDENCE OF THE CHEMICAL PROPERTIES OF PT-RH SURFACES
R.M. WOLF, M.J. DEES et B.E. NIEUWENHUYSGorlaeus Laboratories, P.O. Box 9502, NL-2300 RA Leiden, The Netherlands
Abstract
Field emission (FEM) has been used to study the behaviour of Pt-Rh surfaces towards adsorption of nitrogen and CO. Adsorption of CO on a Pt-Rh (50%:50%) FEM tip, previously annealed at about 1600 K, shows a Pt-like behaviour of the Pt-Rh tip. On a Pt-Rh(12%:88%) tip, the work function change, caused by nitrogen adsorption, was found to vary with annealing temperature from -0.3 eV following previous annealing at 650K to -0.6 eV after annealing at 1450K. Both the FEM pattern and the work function change point towards a platinum surface enrichment of the Pt-Rh alloy, in particular, following previous annealing at a temperature of 1000K and higher. The most drastic changes in surface composition take place around 1000K on the rough surfaces of the tip.