Interactions of Alcohols with Hydroxyl- and Methyl-Terminated Self-Assembled Monolayer Surfaces Studied by Temperature-Programmed Desorption

The interactions of low-molecular-weight n -alcohols ( n -C x H 2 x +1 OH for x = 1−6) with 11-mercaptoundecanol (HO(CH 2 ) 11 SH) or octadecyl mercaptan (CH 3 (CH 2 ) 17 SH) adsorbed onto a nickel(111) single-crystal surface were studied by temperature-programmed desorption (TPD). Angle-dependent X-ray photoelectron spectroscopy (ADXPS) was used to characterize the adsorption of HO(CH 2 ) 11 SH and CH 3 (CH 2 ) 17 SH molecules to determine their arrangements on the nickel(111) surface. The TPD spectra for the desorption of alcohols from the hydroxyl-terminated and the methyl-terminated self-assembled monolayer surfaces at various alcohol fluences were analyzed by the threshold TPD method (TTPD) to determine their desorption energies as a function of the alcohol fluence. The TTPD-calculated alcohol desorption energies from the hydroxyl-terminated surface increased from 10 to 20 kJ mol -1 for the lowest fluences to 40−60 kJ mol -1 for the highest fluences; from the methyl-terminated surface the desorption energy increased from 10 to 25 kJ mol -1 for the lowest fluences to 45−55 kJ mol -1 for the highest fluences.