Low temperature decomposition of ethylene over Ni(100): Evidence for vinyl formation |
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| Institution: | 1. Department of Environmental Medicine, University of Rochester, 575 Elmwood Ave, Box EHSC, Rochester, NY 14642, United States;2. Department of Anthropology, University of California, Santa Barbara, CA 93106-3210, United States;3. Department of Anthropology, Yale University, 10 Sachem St., New Haven, CT 06511, United States;4. Department of Obstetrics and Gynecology, University of Rochester, Rochester, NY 14642, United States;5. Department of Epidemiology, Rutgers School of Public Health, Environmental and Occupational Health Sciences Institute, Piscataway, NJ 08854, United States;1. Materials and Electronic Systems Laboratory, University of Bordj-Bou-Arréridj, 34000 Bordj-Bou-Arréridj, Algeria;2. Laboratory of Materials Physics and its Applications, University of M’sila, 28000 M’sila, Algeria;1. Lobachevsky State University of Nizhny Novgorod, Gagarin av. 23/3, 603950 Nizhny Novgorod, Russia;2. Department of Physics and I3N, University of Aveiro, 3810-193 Aveiro, Portugal;3. National University of Science and Technology “MISiS”, 119049 Moscow, Russia;1. Dept. of Computer Science, Shanghai Normal University, No. 100 Guilin Road, Shanghai 200234, China;2. Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China;3. Shanghai Key Lab of Modern Optical System and Engineering Research Center of Optical Instrument and System, Ministry of Education, University of Shanghai for Science and Technology, China;4. State Key Laboratory of Millimeter Waves, Southeast University, Nanjing 210096, China |
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| Abstract: | Thermal programmed desorption (TPD), high resolution electron energy loss spectroscopy (HREELS), and time-resolved laser-induced desorption (LID) have been used to study the chemisorption and decomposition of ethylene over Ni(100). Ethylene adsorbs molecularly on this surface at temperatures below 150 K. The molecule is π bonded in this state, showing very little rehybridization. At coverages below half saturation, decomposition to vinyl plus a hydrogen atom occurs unimolecularly with a rate constant of (8.0 ± 2.0) × 10−2 s−1 at 170 K. A strong kinetic isotope effect was observed; vinyl formation from C2D4 does not occur until about 200 K. The proposal of vinyl as the intermediate is supported by studies with C2H4, 1,1− and 1,2−C2D2H2, and C2D4. The reaction is slower at saturation coverages, where molecular desorption is still seen above 200 K. Vinyl decomposes further at 230 K to form an acetylenic fragment. |
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