In situ infrared external reflection spectroscopy as a probe of the interactions at the liquid-solid interface of long-chain alkanethiol monolayers at gold

The in situ infrared external reflection spectra of a monolayer film of n-octadecanethiol at gold in aqueous and various nonaqueous solvents are reported. Differences in the peak positions and widths of bands in the C-H stretching region relative to an ex situ (dry N{sub 2} atmosphere) spectrum provide preliminary insights into the interactions between solvent and monolayer. Changes in the width and positions of the CH{sub 3} stretches, which qualitatively correlate with the polarizability of the solvent, suggest a slight increase in conformational disorder near the chain terminus.