Initial sticking probability of O 2 on Cu(4 1 0)

Abstract

We present here a supersonic molecular beam investigation of the initial sticking probability ( S 0) for the O 2/Cu(4 1 0) system. Over the temperature range between 130 and 800 K adsorption occurs dissociatively and S 0 increases up to ∼0.7 with beam energy, indicating that the process is activated. S 0 is larger for angles corresponding to molecules impinging on the step rises, implying that defects are more reactive than terrace atoms. The saturation value of S 0 is however lower than for the parent low Miller index surfaces; this indicates that the reactivity at nanosized terraces is reduced compared to extended Cu(1 0 0) faces. A precursor mediated adsorption path is observed at the lowest translational energy ( E i ) below 150 K, as in the case of O 2/Cu(1 1 0) and at variance with O 2/Cu(1 0 0). At low T and higher energy and for all E i at T > 150 K, adsorption occurs directly, yielding a sticking probability independent of surface temperature.