title: Identification of alcohol conformers by Raman spectra in the C-H stretching region.
abstract: The spontaneous polarized Raman spectra of normal and deuterated alcohols (C2-C5) have been recorded in the C-H stretching region. In the isotropic Raman spectra, a doublet of -CαH stretching vibration is found for all alcohols at below 2900 cm(-1) and above 2950 cm(-1). By comparing the experimental and calculated spectra of various deuterated alcohols, the doublets are attributed to the -CαH stretching vibration of different conformers. For ethanol, the band observed at 2970 cm(-1) is assigned as the stretching vibration of -CαH in the Cα-O-H plane of the gauche-conformer, while the band at 2895 cm(-1) is contributed from both the -CαH2 symmetrical stretching vibration of the trans-conformer and the -CαH stretching vibration out of the Cα-O-H plane of the gauche-conformer. The population of gauche-conformer is estimated to be 54% in liquid ethanol. For the larger alcohols, the same assignments for the doublet are obtained, and the populations of gauche-conformers with plane carbon skeleton are found to be slightly larger than that of ethanol, which is consistent with results from molecular dynamics simulations.
authors.forename: Lin
authors.initials: L
authors.lastname: Chen
authors.forename: Weiduo
authors.initials: W
authors.lastname: Zhu
authors.forename: Ke
authors.initials: K
authors.lastname: Lin
authors.forename: Naiyin
authors.initials: N
authors.lastname: Hu
authors.affiliation: §School of Physics and Material Science, Anhui University, Hefei, Anhui 230039, China.
authors.forename: Yuanqin
authors.initials: Y
authors.lastname: Yu
authors.forename: Xiaoguo
authors.initials: X
authors.lastname: Zhou
authors.forename: Lan-Feng
authors.initials: LF
authors.lastname: Yuan
authors.forename: Shui-Ming
authors.initials: SM
authors.lastname: Hu
authors.forename: Yi
authors.initials: Y
authors.lastname: Luo
mesh_terms: D000433:1-Propanol / Q000737:chemistry*; D003903:Deuterium; D000431:Ethanol / Q000737:chemistry*; D006860:Hydrogen Bonding; D012984:Software; D013059:Spectrum Analysis, Raman / Q000379:methods*
chemical_list: D000431:Ethanol; D000433:1-Propanol; D003903:Deuterium