Interfacial Interactions between a Carboxyl-Terminated Monolayer and Various n-Alcohols

The interactions of vapor-deposited methanol, ethanol, 1-propanol, and 1-hexanol with an 11-mercaptoundecanoic acid (HOOC(CH2)10SH) self-assembled monolayer adsorbed on a nickel(111) single crystal were studied in ultrahigh vacuum by temperature-programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS). The peak shapes of the TPD spectra for methanol, ethanol, and propanol desorption are similar, suggesting that these alcohols undergo similar desorption processes. Their peak desorption temperatures at the lowest submonolayer fluences increased with the number of carbons in the alcohol, suggesting that the methyl and methylene groups, as well as the hydroxyl group, participate in the adsorbed alcohol monolayer's interactions at the acid-terminated self-assembled monolayer surface. Threshold TPD (TTPD) was used for a quantitative analysis of the desorption spectra as a function of coverage. The structure and behavior of hexanol's desorption spectra suggest a different desorption process than it...