A statistical model for flash thermal desorption of carbon dioxide from polycrystalline molybdenum

The interaction of CO2 with a polycrystalline molybdenum-foil (Mo-foil) was previously studied at 77 K through mass-resolved Rash thermal desorption s pectroscopy (FTDS). From the results, a statistical model was developed wit h two kinds of sites (bridge and hollow type), CO2 can adsorb on both but d issociates only on hollow ones. The proposed model reproduces the evolution of desorption peak areas as a function of CO2 exposure without using any f itting parameter. Because of the sample polycrystallinity, all desorption p eaks were fitted assuming a Gaussian distribution of desorption energies wi th a pre-exponential factor of 10(13). Values of similar to 60.6, similar t o 126.9 and similar to 158.7 kJ/mol were obtained for the desorption energi es of CO2 from alpha (1), beta (1) and gamma (1) states, respectively, whil e 73.1 and 110.6 kJ/mol correspond to the CO alpha (2) and beta (2) desorpt ion peaks. (C) 2001 Elsevier Science B.V. All rights reserved.