The chemisorption of Co on Rh(111) |
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Authors: | PA Thiel ED Williams JT Yates WH Weinberg |
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Institution: | Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA |
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Abstract: | The adsorption of CO on Rh(111) has been studied by thermal desorption mass spectrometry and low-energy electron diffraction (LEED). At temperatures below 180 K, CO adsorbs via a mobile precursor mechanism with sticking coefficient near unity. The activation energy for first-order CO desorption is 31.6 kcal/mole (νd = 1013.6s?1) in the limit of zero coverage.As CO coverage increases, a (√3 ×√3)R30u overlayer is produced and then destroyed with subsequent formation of an overlayer yielding a (2 × 2) LEED pattern in the full coverage limit. These LEED observations allow the absolute assignment of the full CO coverage as 0.75 CO molecules per surface Rh atom. The limiting LEED behavior suggests that at full CO coverage two CO binding states are present together. |
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