The interaction of CO, NO, and O₂ with sodium‐promoted Rh(100) surfaces

The promotor effect of Na on the dissociative adsorption of CO, NO, and O₂ at 300 K on Rh(100) has been studied by work function measurements and photoemission spectroscopy using synchrotron radiation in the photon energy range hν=15–35 eV. Preadsorption of Na lowers the work function up to −4.2 eV. Below a critical Na concentration, the work function increases again by ∼0.9 eV by coadsorption of CO, NO, and O₂. Compared to clean Rh(100), the saturation exposure of the dissociative adsorption of NO and O₂ is about ten times greater for Na/Rh(100). The promotional effect of Na is less pronounced for the coadsorption of CO, which shows only fractional dissociation at 300 K.