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 kine tics of ethylidyne in the presence of coadsorbates on Ru(001). The res ults demonstrate that the stabilizing effect of coadsorbed CO and hydr ogen is significantly enhanced at elevated pressure, supporting a mode l wherein an empty neighboring metal site is required before decomposi tion can proceed. We identify a weakly adsorbed CO species in 3-fold h ollow sites in close proximity to the ethylidyne, whose coverage is co ntrolled by the CO pressure at elevated temperatures. The results demo nstrate the importance of weakly adsorbed species at high coverage in controlling surface reactions at elevated pressures and temperatures.