Adsorption and reactions of CH2I2 on Ru(001) surface

A. Kis, K. C. Smith, J. Kiss, F. Solymosi

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

The adsorption and dissociation of CH2I2 were studied at 110 K with the aim of generating CH2 species on the Ru(001) surface. The methods used included X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), temperature programmed desorption (TPD), Auger electron spectroscopy (AES) and work function measurements. Adsorption of CH2I2 is characterized by a work function decrease (0.96 eV at monolayer), indicating that adsorbed CH2I2 has a positive outward dipole moment. Three adsorption states were distinguished: a multilayer (Tp = 200 K), a weakly bonded state (Tp = 220 K) and an irreversibly adsorbed state. A new feature is the formation of CH3I, which desorbs with Tp = 160 K. The adsorption of CH2I2 at 110 K is dissociative at submonolayer, but molecular at higher coverages. Dissociation of the monolayer to CH2 and I proceeded at 198-230 K, as indicated by a shift in the I(3d5/2) binding energy from 620.6 eV to 619.9 eV. A fraction of adsorbed CH2 is self-hydrogenated into CH4 (Tp = 220 K), and another one is coupled to di-σ-bonded ethylene, which - instead of desorption - is converted to ethylidyne at 220-300 K. Illumination of the adsorbed CH2I2 initiated the dissociation of CH2I2 monolayer even at 110 K, and affected the reaction pathways of CH2.

Original languageEnglish
Pages (from-to)190-202
Number of pages13
JournalSurface Science
Volume460
Issue number1-3
DOIs
Publication statusPublished - Jul 20 2000

Keywords

  • Alkanes
  • Alkynes
  • Ruthenium
  • Single crystal surfaces
  • Surface photochemistry
  • Thermal desorption spectroscopy
  • X-ray photoelectron spectroscopy

ASJC Scopus subject areas

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

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