An IRAS study of CO bonding on Sn/Pt(1 1 1) surface alloys at maximal pressures of 10 Torr |
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Authors: | Adrian Hightower M Dolores Perez |
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Institution: | a Occidental College, Physics, 1600 Campus Road, Los Angeles, CA 90041, USA b University of Southern California, Los Angeles, CA 90089, USA c Lehigh University, Bethlehem, PA 18015, USA |
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Abstract: | The adsorption of CO on Pt(1 1 1), (2 × 2) and (√3 × √3)R30° Sn/Pt(1 1 1) surface alloys has been studied using temperature programmed desorption (TPD), low energy electron diffraction (LEED) and infrared reflection adsorption spectroscopy (IRAS). The presence of Sn in the surface layer of Pt(1 1 1) reduces the binding energy of CO by a few kcal/mol. IRAS data show two C-O stretching frequencies, ∼2100 and ∼1860 cm−1, corresponding to atop and bridge bonded species, respectively. Bridge bonded stretching frequencies are only observed for Pt(1 1 1) and (2 × 2) Sn/Pt(1 1 1) alloy surfaces. A slight coverage dependence of the vibrational frequencies is observed for the three surfaces. High pressure IRAS experiments over a broad temperature range show no indication of bridge bonded CO on any of the three surfaces. Direct CO adsorption on Sn sites is not observed over the measured temperature and pressure ranges. |
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Keywords: | Carbon-monoxide Pt(1 1 1) Platinum Catalyst Spectroscopy CO chemisorption Pt3Sn Sn-Pt alloy FTIR IRAS |
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