1. Kinetically Favored Adsorbate Ordering: Hydrogen and Iodine on the Si(100)-2 × 1 Surface
- Author
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Danesha R. Fitzgerald, Ankit G. Shah, Andrew V. Teplyakov, K. M. Bulanin, and Douglas J. Doren
- Subjects
Ethylene ,Hydrogen ,Annealing (metallurgy) ,Infrared spectroscopy ,chemistry.chemical_element ,Kinetic energy ,Surfaces, Coatings and Films ,Condensed Matter::Materials Science ,Crystallography ,chemistry.chemical_compound ,Adsorption ,chemistry ,Computational chemistry ,Desorption ,Physics::Atomic and Molecular Clusters ,Materials Chemistry ,Density functional theory ,Physics::Atomic Physics ,Physics::Chemical Physics ,Physical and Theoretical Chemistry - Abstract
An equimolar mixture of hydrogen and iodine atoms adsorbed on the Si(100) surface is generated by adsorption of iodoethane and annealing to 570 K (which causes ethyl groups to undergo hydrogen elimination and ethylene to desorb). Multiple internal reflection-Fourier transform infrared spectroscopy (MIR-FTIR) shows that the adsorbed hydrogen is distributed among several configurations. After annealing to 700 K, the spectrum shows only a single configuration, which is assigned to surface dimers that are occupied by one hydrogen and one iodine atom. Density functional theory calculations indicate that these mixed-occupation dimers are not energetically favored over other doubly occupied configurations (two H atoms or two I atoms). This evidence indicates that, in contrast to other ordering phenomena in surface adlayers, the ordering in this case is a kinetic effect and is not driven by thermodynamics.
- Published
- 2002
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