A field emission study of carbon monoxide on hcp metals rhenium and ruthenium

Abstract

The surface migration, work function increments, and desorption of carbon monoxide on two hcp metals, rhenium and ruthenium, were observed with field emission techniques. Carbon monoxide is weakly bound to ruthenium and more strongly bound to rhenium. For a complete monolayer, the work function increment is 1.3 eV for ruthenium and 0.8 eV for rhenium. Surface migration commences at a readily observable rate at about 125 K on ruthenium. The migration is characterized by a sharp boundary that becomes boundary free in the later stages. Because desorption precedes surface migration for CO on rhenium, the onset of migration is ill defined. Two well defined binding states α and α, are seen for CO on rhenium.