Electron energy loss characterization of NO on Rh(111). I. NO coordination and dissociation

摘要

Electron energy loss spectroscopy (EELS) has been used to study the adsorption of nitric oxide on Rh(111). NO adsorbs in twofold bridge sites at all coverages. The dissociation rate of NO on this surface at low coverage has been measured directly using EELS. The first order dissociation rate parameters areEa=19.2plusmn;0.3 kcal/mol and ngr;(1)0=1times;1014plusmn;0.3thinsp;sminus;1at thgr;NOape;0.2. Ordered low energy electron diffraction (LEED) patterns are observed only for partially dissociated NO adlayers and not for NO adsorbed molecularly at 95 K. Because NO adsorbs in twofold bridge sites at all coverages, the Nndash;O stretching frequency exhibits a 150 cmminus;1shift from zero to saturation coverage.