Weakly chemisorbed CO layer on Rh(100) as detected by reverse flash and field ion appearance energy measurements

Abstract

Using the reverse flash (RF) method, the sticking coefficient and binding energy of CO molecules on Rh(100) are obtained for CO surface densities up to 1.2 × 10 15 cm −2. The presence of weakly bound CO molecules with a binding energy of 0.34 eV is detected at n > 1.0 × 10 15 cm −2. Mass-to-charge-resolved retarding potential analysis of CO + emitted from Rh(100) is performed and absolute values of CO + field ion appearance energy obtained. By applying a thermionic cycle field-dependent values of the binding energy of CO Rh(100) at high coverages are obtained. A comparison of field-free (RF) results and field ion appearance energy spectroscopy (FIAES) data reveals the weakly bound (field-stabilized) CO layer as the origin of CO + field ions emitted from Rh(100) for field ion imaging.