Vibrational study of anharmonicity, supramolecular structure, and hydrogen bonding in two octanol isomers

Results from far-, mid-, and near-infrared spectroscopy are presented and combined with previous dielectric data on 2-ethyl-1-hexanol and 4-methyl-3-heptanol. This yields the electromagnetic absorption spectrum of the two monohydroxy alcohols, presented in terms of the imaginary part of the complex refractive index in a very wide frequency range. Low-frequency Raman measurements and far-infrared spectra hint at differences in the supramolecular structure of the two alcohols. By comparing the wavenumbers and amplitudes of the fundamental and the first overtone of the hydroxyl group’s stretching vibration the temperature dependence of anharmonic effects and hydrogen bond cooperativity is studied.