(Received: January 23, 2004; Accepted for publication: April 5, 2004; Published on Web: August 9, 2004)
The adsorption structure and hyperfine coupling constant of methyl radical CH3 on a boron-containing oxide surface have been studied by means of density functional theory (DFT) calculations. As models for CH3 adsorbed on boron oxide surface, Model-I in which CH3 interacts with a surface B atom and Model-II in which CH3 interacts with a surface B-OH group have been chosen. On the basis of the calculation results, Model-II is found to be a more favorable adsorption site. The proton hyperfine coupling constant of Model-II is calculated to be smaller than that of Model-I; the proton hyperfine coupling constant of Model-I is almost equal to that of free CH3. The reason for the difference between the proton hyperfine coupling constants of Model-I and Model-II has been discussed on the basis of the calculation results. The difference in the proton hyperfine coupling constants can be explained by the spin-polarization mechanism.
Keywords: Methyl radical, Boron oxide, Adsorption site, Hyperfine coupling constant, Density functional theory
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