Surface chemistry of methyl radicals on O/Mo(100) surfaces
Journal Article
·
· Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical
The chemistry of CH{sub 3} 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 CH{sub 3} 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 {theta}{sub o} = 1.4 monolayer (ML) produces exclusively CH{sub 4} and CO, but O/Mo(100) with {theta}{sub o} = 0.9 and 0.4 ML produce significant amounts of C{sub 2+} alkenes in addition to CH{sub 4} and CO. HREELS shows that the CH{sub 3} groups are bound to surface Mo atoms, not to surface oxygen. On 1.4 ML-O, the CH{sub 3} groups are stable at 320 K and have a symmetry lower than C{sub 3{nu}}. On 0.9 ML-O and 0.4 ML-O, some CH{sub 3} groups decompose to methylene groups, which react with intact CH{sub 3} groups to form surface alkyl groups. The surface species at 320 K appear to be controlled by the preadsorbed oxygen coverage, depending on whether {theta}{sub o} < 1 ML or {theta}{sub o} > 1 ML. CH{sub 4} is formed via hydrogenation of CH{sub 3} groups by surface hydrogen that is a product of CH{sub 3} decomposition. C{sub 2+} alkene products are formed by {beta}-hydrogen elimination of surface alkyl groups. When atomic iodine is coadsorbed on O/Mo(100), the alkene yield in TPD is significantly reduced.
- Research Organization:
- Northwestern Univ., Evanston, IL (US)
- OSTI ID:
- 20034429
- Journal Information:
- Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical, Journal Name: Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical Journal Issue: 14 Vol. 104; ISSN 1089-5647; ISSN JPCBFK
- Country of Publication:
- United States
- Language:
- English
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