AGING OF ALKANETHIOL SELF-ASSEMBLED MONOLAYERS

Self-assembled monolayers of three straight-chain alkanethiols [CH3(CH 2)(n)SH, n = 11, 15, 17] have been formed on a gold substrate from cyc lohexane solution and characterised using IR spectroscopy. Over a peri od of ca. six months, the relative intensities of the C-H stretching b ands in the IR spectra were observed to change. These changes are expl ained by a tilting of the molecules from their initial position away f rom the surface normal upon oxidation of the thiolate root. This tempo ral dependence of the tilt angle has implications for the stability of self-assembled monolayers.