Chemical structure and orientation of ethylene on Si(114)-(2 x 1)/c(2 x 2).
The basic chemical structure and orientation of ethylene chemisorbed on Si(114)-(2 x 1) at submonolayer coverage is characterized in ultrahigh vacuum using transmission Fourier transform infrared (FTIR) spectroscopy. The spectra are consistent with di-sigma bonding of ethylene to the surface with a preferential molecular orientation over macroscopic lengths. These results are supported by density functional theory (DFT) calculations of vibrational frequencies for optimized ethylene-Si(114) structures occupying the dimer and rebonded atom surface sites. A detailed analysis of the strong angular and polarization dependence of the C-H stretching mode intensities is also consistent with the adsorption structures identified by DFT, indicating that ethylene chemisorbs with the C-C bond axis parallel to the structural rows oriented along the [10] direction on the Si(114)-(2 x 1) surface. The results indicate that the unique structure of this surface makes it an excellent template for elucidating relationships between surface structure and organic reaction mechanisms on silicon.
Naval Research Laboratory, Chemistry Division, 4555 Overlook Avenue, SW, Washington, D.C. 20375-5342.
D E
DE
Barlow
S C
SC
Erwin
A R
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Laracuente
L J
LJ
Whitman
J N
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Russell