Polar ordering at the liquid-vapor interface of n-alcohols (C1-C8)

Vibrational spectra of the liquid-vapor interfaces of methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol and octanol were obtained in the CH and OH stretching region using infrared-visible sum-frequency generation. All alcohols studied are polar oriented at such interfaces with the alkyl chain pointing away from the liquid. For hexanol, heptanol, and octanol, the spectra show the presence of trans-gauche defects in the alkyl chain. For all alcohols, the shift of spectra to lower frequency in the OH stretching region indicates a well-ordered hydrogen-bonding network at the interface.