Methane dissociation on the step and terrace sites of a Pt(211) single crystal was studied by reflection absorption infrared spectroscopy (RAIRS) at a surface temperature of 120 K. The C—H stretch RAIRS signal of the chemisorbed methyl product species was used to distinguish between adsorption on step and terrace sites allowing methyl uptake to be monitored as a function of incident kinetic energy for both sites. Our results indicate a direct dissociation mechanism on both sites with higher reactivity on steps than on terraces consistent with a difference in an activation barrier height of at least 30 kJ/mol. State-specific preparation of incident CH4 with one quantum of antisymmetric (ν3) stretch vibration further increases the CH4 reactivity enabling comparison between translational and vibrational activation on both steps and terraces. The reaction is modeled with first principles quantum theory that accurately describes dissociative chemisorption at different sites on the surface.
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Methane dissociation on the steps and terraces of Pt(211) resolved by quantum state and impact site
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7 January 2018
Research Article|
January 02 2018
Methane dissociation on the steps and terraces of Pt(211) resolved by quantum state and impact site
Helen Chadwick
;
Helen Chadwick
a)
1
Laboratoire de Chimie Physique Moléculaire, Ecole Polytechnique Fédérale de Lausanne
, 1015 Lausanne, Switzerland
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Han Guo;
Han Guo
2
Department of Chemistry, University of Massachusetts
, Amherst, Massachusetts 01003, USA
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Ana Gutiérrez-González;
Ana Gutiérrez-González
1
Laboratoire de Chimie Physique Moléculaire, Ecole Polytechnique Fédérale de Lausanne
, 1015 Lausanne, Switzerland
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Jan Paul Menzel;
Jan Paul Menzel
a)
2
Department of Chemistry, University of Massachusetts
, Amherst, Massachusetts 01003, USA
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Bret Jackson
;
Bret Jackson
b)
2
Department of Chemistry, University of Massachusetts
, Amherst, Massachusetts 01003, USA
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Rainer D. Beck
Rainer D. Beck
b)
1
Laboratoire de Chimie Physique Moléculaire, Ecole Polytechnique Fédérale de Lausanne
, 1015 Lausanne, Switzerland
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a)
Current address: Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands.
b)
Electronic addresses: jackson@chem.umass.edu and rainer.beck@epfl.ch
J. Chem. Phys. 148, 014701 (2018)
Article history
Received:
October 07 2017
Accepted:
November 17 2017
Citation
Helen Chadwick, Han Guo, Ana Gutiérrez-González, Jan Paul Menzel, Bret Jackson, Rainer D. Beck; Methane dissociation on the steps and terraces of Pt(211) resolved by quantum state and impact site. J. Chem. Phys. 7 January 2018; 148 (1): 014701. https://doi.org/10.1063/1.5008567
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