The Reaction of Acetylene with Ni(100) and Ni(110) Surfaces at Room Temperature.
Abstract
Ultraviolet photoemission spectroscopy using Hv=21.2eV and filtered 40.8eV radiation as well as temperature programmed thermal desorption spectroscopy are used to investigate the chemical reaction of acetylene with Ni(100) and Ni(110) surfaces at room temperature. Striking crystallographic effects and several coexisting phases are observed and found to be coverage and temperature dependent. A methodology is described to predict the relative energy levels for a variety of adsorbed hydrocarbon fragments on Ni surfaces. Such levels together with the thermal desorption spectra are used to identify the, observed species. In particular, CH and CCH species are isolated on Ni(100) and Ni(110) surfaces, respectivelyvia low temperature adsorption and subsequent pulsed sample warming experiments. The room temperature adsorption phases are deduced using these ionization levels together with those of chemisorbed acetylene, atomic hydrogen and carbon. At room temperature on Ni(100) H, C, CH and C2H2 species form together below 2 Langmuirs exposure while CH species form thereafter, up to saturation exposure of 10 Langmuirs. On Ni(110), H and CCH species form below 1.5 Langmuirs exposure followed by the formation of CH2 and likely CH species. The relative stabilities of these species at elevated temperatures is: C2H2<C2H<CH<CH2. A model for the bonding of acetylene and its reaction to form CCH species on Ni(110) is proposed. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1979
- Accession Number
- ADA078630
Entities
People
- J. E. Demuth
Organizations
- IBM Thomas J. Watson Research Center