The adsorption and structure of carbon monoxide on ethylidyne-covered Pd(111)

摘要

A quarter of a monolayer of carbon monoxide (CO) adsorbs on ethylidyne-covered Pd(1 1 1) (ethylidyne saturation coverage, 0.25 monolayers) at 300 K, compared to the saturation coverage of 0.55 monolayers for CO on clean Pd(1 1 1). Infrared and temperature-programmed desorption data reveal that CO adsorbs on the hexagonal-close-packed, threefold hollow site on ethylidyne-covered Pd(1 1 1). This, in turn, suggests that ethylidyne species on Pd(1 1 1) occupy face-centered-cubic, threefold hollow sites. Atop sites become occupied when an ethylidyne-covered Pd(l 1 1) surface is pressurized with 10(-2) Torr of CO, and no additional CO appears to adsorb when the surface is pressurized with 5 Torr of CO. (C) 2000 Elsevier Science B.V. All rights reserved. References: 20