Infrared Vibrational Spectroscopy of Isotopically Labeled Ethyl-Terminated Si(111) Surfaces Prepared Using a Two-Step Chlorination/Alkylation Procedure

Fourier transform infrared (FTIR) spectroscopy was used to investigate C2H5−Si(111) surfaces prepared using a chlorination/alkylation method. After alkylation, in addition to ethyl groups, such surfaces showed the presence of hydrogen bonded to atop silicon surface atoms. Systematic isotopic substitution of protic solvents and reagents with their fully or partially deuterated counterparts revealed the origin of the surface-bound hydrogen on the C2H5−Si(111) surfaces. The presence or absence of the Si−H stretch at 2080 cm−1 and the Si−D stretch at ∼1510 cm−1, respectively, indicated that the hydrogen originated from the methyl group of the ethyl Grignard reagent.