lodomethane dissociation on Cu(111)

Bonding and chemistry of adsorbed methyl groups

Jong-Liang Lin, Brian E. Bent

Research output: Contribution to journalArticle

83 Citations (Scopus)

Abstract

The chemistry of iodomethane on a Cu( 111) surface has been studied by a combination of work function measurements, Auger electron spectroscopy, high-resolution electron energy-loss spectroscopy, and temperature programmed reaction spectroscopy. Our results show that iodomethane dissociates below 200 K to form iodine atoms and methyl groups, which are stable up to 400 K. At low coverages, the methyl groups bond with C, symmetry and at high coverages with C3t. symmetry. The methyl group stretching frequency on the surface is redshifted by —150 - cm 1 compared to that of iodomethane. Possible bonding sites as well as reasons for the stretching mode softening and coverage-dependent orientation of methyl groups are discussed. The surface reactions of methyl groups on Cu( 111) are coverage dependent. At low coverages, CH3(a) decomposes at 450 K to evolve methane, ethylene, and propylene, a elimination from methyl groups to produce CH2 and H is the rate-determining step in forming these products. At higher coverages, methyl coupling also occurs to evolve ethane.

Original languageEnglish
Pages (from-to)2202-2209
Number of pages8
JournalJournal of Vacuum Science and Technology A: Vacuum, Surfaces and Films
Volume10
Issue number4
DOIs
Publication statusPublished - 1992 Jan 1

Fingerprint

Stretching
dissociation
chemistry
Electron energy loss spectroscopy
Surface reactions
Auger electron spectroscopy
Ethane
Iodine
Propylene
Ethylene
Methane
Spectroscopy
Atoms
symmetry
propylene
ethane
softening
Temperature
surface reactions
spectroscopy

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

Cite this

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abstract = "The chemistry of iodomethane on a Cu( 111) surface has been studied by a combination of work function measurements, Auger electron spectroscopy, high-resolution electron energy-loss spectroscopy, and temperature programmed reaction spectroscopy. Our results show that iodomethane dissociates below 200 K to form iodine atoms and methyl groups, which are stable up to 400 K. At low coverages, the methyl groups bond with C, symmetry and at high coverages with C3t. symmetry. The methyl group stretching frequency on the surface is redshifted by —150 - cm 1 compared to that of iodomethane. Possible bonding sites as well as reasons for the stretching mode softening and coverage-dependent orientation of methyl groups are discussed. The surface reactions of methyl groups on Cu( 111) are coverage dependent. At low coverages, CH3(a) decomposes at 450 K to evolve methane, ethylene, and propylene, a elimination from methyl groups to produce CH2 and H is the rate-determining step in forming these products. At higher coverages, methyl coupling also occurs to evolve ethane.",
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lodomethane dissociation on Cu(111) : Bonding and chemistry of adsorbed methyl groups. / Lin, Jong-Liang; Bent, Brian E.

In: Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films, Vol. 10, No. 4, 01.01.1992, p. 2202-2209.

Research output: Contribution to journalArticle

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N2 - The chemistry of iodomethane on a Cu( 111) surface has been studied by a combination of work function measurements, Auger electron spectroscopy, high-resolution electron energy-loss spectroscopy, and temperature programmed reaction spectroscopy. Our results show that iodomethane dissociates below 200 K to form iodine atoms and methyl groups, which are stable up to 400 K. At low coverages, the methyl groups bond with C, symmetry and at high coverages with C3t. symmetry. The methyl group stretching frequency on the surface is redshifted by —150 - cm 1 compared to that of iodomethane. Possible bonding sites as well as reasons for the stretching mode softening and coverage-dependent orientation of methyl groups are discussed. The surface reactions of methyl groups on Cu( 111) are coverage dependent. At low coverages, CH3(a) decomposes at 450 K to evolve methane, ethylene, and propylene, a elimination from methyl groups to produce CH2 and H is the rate-determining step in forming these products. At higher coverages, methyl coupling also occurs to evolve ethane.

AB - The chemistry of iodomethane on a Cu( 111) surface has been studied by a combination of work function measurements, Auger electron spectroscopy, high-resolution electron energy-loss spectroscopy, and temperature programmed reaction spectroscopy. Our results show that iodomethane dissociates below 200 K to form iodine atoms and methyl groups, which are stable up to 400 K. At low coverages, the methyl groups bond with C, symmetry and at high coverages with C3t. symmetry. The methyl group stretching frequency on the surface is redshifted by —150 - cm 1 compared to that of iodomethane. Possible bonding sites as well as reasons for the stretching mode softening and coverage-dependent orientation of methyl groups are discussed. The surface reactions of methyl groups on Cu( 111) are coverage dependent. At low coverages, CH3(a) decomposes at 450 K to evolve methane, ethylene, and propylene, a elimination from methyl groups to produce CH2 and H is the rate-determining step in forming these products. At higher coverages, methyl coupling also occurs to evolve ethane.

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