The O-H Stretching Vibrational Overtones and Molecular Conformations of iso-Propanol

The O-H stretching v =4, 5 vibrational overtone spectra of iso-propanol are measured by using highly sensitive cavity ring down spectroscopy (CRDS), where three peaks are observed for each vibrational level. They are assigned to the absorption of the O-H stretching vibrations of molecular conformations. Band intensity formula of overtone for CRDS is given,and band intensities of each band for different levels are obtained. Meanwhile, the mechanical frequencies X1, anharmonicities X2, and dissociation energies D are evaluated by the local mode theory. The different possible conformations of the molecule are optimized by density function theory (DFT) B3LYP/6-31+G* theory methods, where it is confirmed that only the two conformations of trans and gauche forms are stable in this molecule. The calculated O-H stretching frequencies and stability of the molecule are in good agreement with the experimental results.