Adsorption of hydrogen, carbon monoxide and nitrogen on rhenium(0001) and copper overlayers on rhenium(0001)

Abstract

The interaction of hydrogen, carbon monoxide, and nitrogen with Re(0001) and with Re(0001) covered with submonolayer to multilayer Cu has been studied by thermal desorption spectroscopy (TDS) and low-energy electron diffraction (LEED). The adsorption of H{sub 2} on clean Re(0001) induces a 2 {times} 2 superstructure that can be produced by H{sub 2} exposure over a wide temperature range (110-300 K). cu deposition on Re(0001) induces a new hydrogen desorption state with a higher bonding energy than that from bulk Cu. Cu overlayers result in the attentuation of the H{sub 2} desorption peak associated with the Re substrate. Adsorption of CO on a Re(0001) surface with varying amounts of Cu shows that at low Cu coverages (< 2 ML), a new desorption state is present, with a corresponding binding energy higher than that for bulk Cu and lower than that for clean Re(001). This state is interpreted to correspond to CO adsorbed at Cu sites perturbed by the underlying Re. At higher Cu coverages ({approx} 5 ML), the CO TDS features are essentially the same as those found for bulk Cu. No new TDS states of nitrogen have been observed following nitrogen adsorption on Cu-covered Re. The TDS features frommore » the Re substrate are greatly reduced by Cu deposition, consistent with Cu serving as a simple site-blocking agent to the adsorption and dissociation of nitrogen on Re.« less