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Molecular desorption of methyl halides from GaAs(110): The role of lateral dipole--dipole interaction between adsorbates

Journal Article · · Journal of Chemical Physics; (United States)
DOI:https://doi.org/10.1063/1.468004· OSTI ID:7177743
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  1. Columbia Radiation Laboratory, Columbia University, New York, New York 10027 (United States)
Temperature programmed desorption (TPD) spectra of CH[sub 3]X (X=Cl, Br, I) from GaAs(110) were recorded with a heating rate of 5 K/s for coverages from less than 0.1 to 2 ML, where methyl halides desorb molecularly, i.e., without dissociation. The shapes of the TPD spectra are strongly coverage dependent with the peak temperature of desorption decreasing with increasing coverage, especially for the submonolayer region. A model incorporating dipole--dipole repulsive interactions between the adsorbed molecules and which was previously proposed for the desorption of adsorbed molecules from metal surfaces has been employed to fit our TPD spectra. The fit gives the activation energy, effective dipole moment, and effective polarizability for the adsorbate. The resulting dipole moment and polarizability are less than the gas-phase molecular values, suggesting the importance of an ordered adsorption orientation. [copyright] [ital 1994][ital American] [ital Institute] [ital of] [ital Physics].
DOE Contract Number:
FG02-90ER14104
OSTI ID:
7177743
Journal Information:
Journal of Chemical Physics; (United States), Journal Name: Journal of Chemical Physics; (United States) Vol. 101:11; ISSN JCPSA6; ISSN 0021-9606
Country of Publication:
United States
Language:
English