Thermal and photoinduced dissociation of CH2I2 on Cu(100) surface

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Abstract

The adsorption and dissociation of CH2I2 were studied at 90-250 K with the aim of generating CH2 on the Cu(100) surface. The methods used included XPS, UPS, TPD, AES, and work function measurements. Adsorption of CH2I2 is characterized by a work function decrease (0.1 eV at the monolayer), indicating that adsorbed CH2I2 has a positive outward dipole moment. Two adsorption states were distinguished: a multilayer and an irreversibly adsorbed state. The adsorption of CH2I2 at 90 K is dissociative at the submonolayer but is molecular at higher coverages. Dissociation of the monolayer proceeded at 192-204 K, as indicated by a shift in the I(3d5/2) binding energy from 620.5 to 619.7 eV. Illumination of the adsorbed CH2I2 at 90-95 K markedly enhanced the dissociation. The primary products are adsorbed CH2 and I. CH2 is characterized by a C(ls) binding energy of 283.9 eV and by a photoemission signal at 5.4-5.6 eV. CH2 species reacted to form C2H4 at 160-230 K, which desorbed in a pseudo-first-order process with Tp = 240 K. The high peak temperature suggests the formation of a more strongly adsorbed, very likely di-σ- bonded ethylene. The self-hydrogenation of CH2, observed on platinum metals, did not occur on Cu(100).

Original languageEnglish
Pages (from-to)5397-5404
Number of pages8
JournalJournal of Physical Chemistry B
Volume101
Issue number27
Publication statusPublished - Jul 3 1997

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thermal dissociation
dissociation
Adsorption
adsorption
Binding energy
Monolayers
binding energy
Platinum metals
Dipole moment
Photoemission
Temperature programmed desorption
Hydrogenation
hydrogenation
Ethylene
Multilayers
dipole moments
platinum
ethylene
photoelectric emission
X ray photoelectron spectroscopy

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Engineering(all)

Cite this

Thermal and photoinduced dissociation of CH2I2 on Cu(100) surface. / Kovács, I.; Solymosi, F.

In: Journal of Physical Chemistry B, Vol. 101, No. 27, 03.07.1997, p. 5397-5404.

Research output: Contribution to journalArticle

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