Site blocking effects in ethylidyne decomposition kinetics on Ru(001) : in-situ-study with infrared reflection absorption spectroscopy at elevated pressure

Utilizing in-situ FT-IRAS, we have investigated the decomposition kinetics of ethylidyne in the presence of coadsorbates on Ru(001). The results demonstrate that the stabilizing effect of coadsorbed CO and hydrogen is significantly enhanced at elevated pressure, supporting a model wherein an empty neighboring metal site is required before decomposition can proceed. We identify a weakly adsorbed CO species in 3-fold hollow sites in close proximity to the ethylidyne, whose coverage is controlled by the CO pressure at elevated temperatures. The results demonstrate the importance of weakly adsorbed species at high coverage in controlling surface reactions at elevated pressures and temperatures. 26 refs., 3 figs.