Surface chemistry of methyl radicals on OTMo(100) surfaces

Seong Han Kim, Peter C Stair

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

The chemistry of CH3 radicals on oxygen-modified Mo(100) surfaces (O/Mo(100)) has been studied using temperature-programmed desorption (TPD) and high-resolution electron energy loss spectroscopy (HREELS). Gas-phase CH3 radicals were produced by pyrolysis of azomethane and dosed on O/Mo(100) at a surface temperature of 320 K. In TPD, O/Mo(100) with θO = 1.4 monolayer (ML) produces exclusively CH4 and CO, but O/Mo(100) with θo = 0.9 and 0.4 ML produce significant amounts of C2+ alkenes in addition to CH4 and CO. HREELS shows that the CH3 groups are bound to surface Mo atoms, not to surface oxygen. On 1.4 ML-O, the CH3 groups are stable at 320 K and have a symmetry lower than C. On 0.9 ML-O and 0.4 ML-O, some CH3 groups decompose to methylene groups, which react with intact CH3 groups to form surface alkyl groups. The surface species at 320 K appear to be controlled by the preadsorbed oxygen coverage, depending on whether θo ≤ 1 ML or θo > 1 ML. CH4 is formed via hydrogenation of CH3 groups by surface hydrogen that is a product of CH3 decomposition. C2+ alkene products are formed by β-hydrogen elimination of surface alkyl groups. When atomic iodine is coadsorbed on O/Mo(100), the alkene yield in TPD is significantly reduced.

Original languageEnglish
Pages (from-to)3035-3043
Number of pages9
JournalJournal of Physical Chemistry B
Volume104
Issue number14
Publication statusPublished - Apr 13 2000

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Surface chemistry
chemistry
Monolayers
Oxygen
oxygen
Alkenes
Temperature programmed desorption
alkenes
Olefins
desorption
Electron energy loss spectroscopy
Carbon Monoxide
methyl radical
Hydrogen
energy dissipation
electron energy
high resolution
hydrogen
products
methylene

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Surface chemistry of methyl radicals on OTMo(100) surfaces. / Kim, Seong Han; Stair, Peter C.

In: Journal of Physical Chemistry B, Vol. 104, No. 14, 13.04.2000, p. 3035-3043.

Research output: Contribution to journalArticle

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