Hydrogen isotope exchange in alkylidynes on Pt(111) |
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| Institution: | 1. Géosciences Rennes, UMR 6118CNRS, Université Rennes1, Campus de Beaulieu, 35042 Rennes, France;2. Utrecht University, Faculty of Earth Science, Budapestlaan 4, 3584 CD Utrecht, The Netherlands;3. University of Oslo, Department of Geosciences, PO Box 1047 Blindern, NO-316 Oslo, Norway;4. Géosciences Montpellier, UMR 5243CNRS, Université Montpellier2, place E. Bataillon, 34095 Montpellier, France;1. University of California Santa Barbara, Department of Earth Science, Santa Barbara, CA 93109-9630, USA;2. University of Leeds, School of Earth and Environment, Leeds, UK;3. Stony Brook University, Department of Geosciences, Stony Brook, NY, United States;4. Vrije Universiteit Amsterdam, Faculty of Earth and Life Sciences, Amsterdam, NL, The Netherlands;1. School of Geosciences, University of Sydney, Australia;2. Geology Department, Lakehead University, 955 Oliver Rd, Thunder Bay, Ontario P7B 5E1, Canada;3. Laboratório de Geologia Isotópica, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil;1. State Key Lab of Marine Geology, Tongji University, Shanghai 20092, China;2. Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA |
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| Abstract: | The exchange of deuterium and hydrogen in ethylidyne and propylidyne on Pt(111) has been studied using temperature programmed desorption and secondary ion mass spectroscopy. Activation energies of near 7 kcal/mol characterize the initial rate of deuterium incorporation into both species. The exchange in ethylidyne is readily described by a sequential exchange model with equal exchange rates for each of the three deuterium atoms. In propylidyne, the situation is quite different in the following respects: (1) comparable incorporation rates require 100-fold higher D2 pressures, and (2) incorporation rates are very nonuniform, some D being incorporated very rapidly and some H remaining unreacted even at very long D2 exposures. Possible active exchange intermediates are discussed. |
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