The adsorption and structure of carbon monoxide on ethylidyne-covered Pd(1 1 1)
نویسندگان
چکیده
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-closepacked, 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(1 1 1) surface is pressurized with 10ÿ2 Torr of CO, and no additional CO appears to adsorb when the surface is pressurized with 5 Torr of CO. Ó 2000 Elsevier Science B.V. All rights reserved.
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