Accession Number : ADA137216

Title :   Vibrational Spectroscopy of Acetylene Decomposition on Palladium (111) and (100) Surfaces.

Descriptive Note : Interim technical rept.,


Personal Author(s) : Kesmodel,L L ; Waddill,G D ; Gates,J A

PDF Url : ADA137216

Report Date : 16 Jan 1984

Pagination or Media Count : 24

Abstract : Vibrational spectra for thermal decomposition of acetylene (C2H2) on (111) and (100) surfaces of palladium obtained with high-resolution electron energy loss spectroscopy (EELS) are described. Of particular interest is the formation of CCH species on both surfaces, which are identified spectroscopically in this context for the first time. On Pd(100) CCH forms with thermal processing of chemisorbed acetylene to approximately 400K but on Pd(111) is co-adsorbed with a triple bond C-CH3 species following 300K C2H2 adsorption. With further annealing to 450K CCH is the dominant species on both surfaces. The EELS spectra indicate that both carbon atoms are involved in the CCH interaction with the surface as implied by a C-C bond order between 1 and 2. In view of recent reports of acetylene trimerization to benzene (C6H6) on Pd surfaces the EELS spectra of C6H6 and isotopic mixtures were also analyzed but no evidence of this reaction was found.

Descriptors :   *Vibrational spectra, *Electron spectroscopy, *Acetylene, *Pyrolysis, Thermal degradation, Thermochemistry, Decomposition, Surface reactions, Palladium, Chemisorption, Catalysis, Annealing, Carbon, Chemical bonds, Stereochemistry, Isotopes

Subject Categories : Organic Chemistry
      Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE