POLARIZATION MODULATION FOURIER-TRANSFORM INFRARED STUDIES OF THE EFFECTS OF SELF-ASSEMBLY TIME ON THE ORDER AND ORIENTATION OF 11-FERROCENYL-1-UNDECANETHIOL MONOLAYERS ON GOLD

The effects of self-assembly time on the order and orientation of 11-f errocenyl-1-undecanethiol (FcC(11)SH) molecular layers on gold were st udied with polarization modulation Fourier transform infrared spectros copy. A comparison between the intensity of the asymmetric methylene s tretching mode of a 1-octadecanethiol monolayer and that of the FcC(11 )SH molecular layer confirmed that the FcC(11)SH molecules formed a se lf-assembled monolayer on the gold surface. The conformational order o f the monolayer increased with longer self-assembly time as evidenced by a decrease in the vibrational frequencies of the methylene stretchi ng modes and a decrease in the full width at half maximum of these ban ds. The peak area of the asymmetric methylene stretch also decreased w ith longer self-assembly time, implying that the FcC(11)SH molecules s tood more erect with respect to the gold surface as the monolayer self -assembled.