Adsorption of Gases on Ruthenium Field Emitters I. Carbon Monoxide and Oxygen

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Abstract
The adsorption and desorption of carbon monoxide and of oxygen on ruthenium have been investigated in a field emission microscope with total current measurements. Neither gas shows high face specificity. Adsorption of CO leads to very high work function increments (up to 1.8 eV at 230 K), although the bond is rather weak (desorption is completed by heating to 550 K). The initial sticking coefficient at 300 K is about 0.5, but decreases faster than proportional to the uncovered portion of the surface. Adsorption of oxygen leads to a work function increase by 1.4 eV at 300 K. Heating to up to 1100 K causes reconstruction accompanied by lowering of the work function, but no desorption. Desorption starts at about 1200 K and is completed at 2000 K.The findings are discussed in context with other work, especially with a recent investigation of adsorption on the hexagonal close‐packed Ru face.