The role of adsorbate structure in the photodissociation dynamics of adsorbed species

Methyl iodide/MgO(100)

D. Howard Fairbrother, K. A. Briggman, Peter C Stair, Eric Weitz

Research output: Contribution to journalArticle

38 Citations (Scopus)

Abstract

The 257 nm photodissociation dynamics of methyl iodide multilayers adsorbed on MgO(100) have been studied using resonantly enhanced multiphoton ionization time-of-flight mass spectrometry (REMPI-TOFMS) to detect both methyl and iodine photofragments. The photofragments result from direct photolysis of the methyl iodide adsorbate. Methyl fragments with a translational and internal energy content comparable to that found in the gas phase dissociation of the isolated molecule are produced. However, the measured I/I* branching ratio is modified in favor of ground state (I) iodine production. Collisionally slowed methyl fragments, characterized by a translational temperature close to that of the surface, are also observed. Iodine fragments with velocities in excess of the gas phase limit are produced as a result of collisional energy transfer between iodine and faster moving methyl photofragments. A small amount of laser induced photodesorption, leading to the production of molecular methyl iodide, was also detected. The observed photofragmentation dynamics can be accounted for based on the ordered antiparallel structure adopted by the adsorbate molecules that are preferentially aligned along the surface normal within the physisorbed layer.

Original languageEnglish
Pages (from-to)7267-7276
Number of pages10
JournalJournal of Chemical Physics
Volume102
Issue number18
Publication statusPublished - 1995

Fingerprint

Photodissociation
Adsorbates
Iodine
photodissociation
iodides
iodine
fragments
Gases
vapor phases
Molecules
Photolysis
internal energy
Energy transfer
Ground state
Ionization
Mass spectrometry
photolysis
molecules
Multilayers
mass spectroscopy

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Cite this

The role of adsorbate structure in the photodissociation dynamics of adsorbed species : Methyl iodide/MgO(100). / Fairbrother, D. Howard; Briggman, K. A.; Stair, Peter C; Weitz, Eric.

In: Journal of Chemical Physics, Vol. 102, No. 18, 1995, p. 7267-7276.

Research output: Contribution to journalArticle

Fairbrother, D. Howard ; Briggman, K. A. ; Stair, Peter C ; Weitz, Eric. / The role of adsorbate structure in the photodissociation dynamics of adsorbed species : Methyl iodide/MgO(100). In: Journal of Chemical Physics. 1995 ; Vol. 102, No. 18. pp. 7267-7276.
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