The adsorption of oxygen at 100 K on Rh(100) has been studied with temperature‐programmed desorption and photoelectron spectroscopy. Oxygen adsorbs with a sticking probability of about 0.8 up to a near saturation coverage of 1.1×1015 atoms/cm2 or three‐fourths of a monolayer coverage on Rh(100). Initial adsorption is dissociative. However, for coverages above half a monolayer a low temperature molecular state, denoted α, which does not exhibit isotopic exchange, desorbs at 150 K. Dissociated oxygen recombines and desorbs in three high temperature or β states. At low coverages oxygen desorbs in a second order state, β3, between 1200 and 1325 K with an activation energy for desorption of 360 kJ/mole (85 kcal/mole). At coverages above half a monolayer, two first order states, β1 and β2, appear at 820 and 920 K, respectively. Their respective heats of desorption are 210 kJ/mole (50 kcal/mole) and 260 kJ/mole (62 kcal/mole). In contrast with previously reported results, no bulk diffusion of adsorbed oxygen atoms into Rh is observed for temperatures up to the onset of oxygen desorption.

This content is only available via PDF.
You do not currently have access to this content.