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New spectral assignment of n‐propanol in the C―H stretching region
Author(s) -
Yu Yuanqin,
Wang Yuxi,
Lin Ke,
Zhou Xiaoguo,
Liu Shilin,
Sun Jin
Publication year - 2016
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.5000
Subject(s) - raman spectroscopy , isotopologue , chemistry , fermi resonance , propanol , carbon fibers , infrared spectroscopy , analytical chemistry (journal) , spectral line , infrared , resonance (particle physics) , crystallography , molecule , materials science , organic chemistry , atomic physics , methanol , physics , astronomy , composite number , optics , composite material
The C―H stretching vibration serves as an important probe for characterizing molecular structures and properties of hydrocarbons. In this work, we present a detailed study on gas‐phase Raman spectrum of n‐propanol in the C―H stretching region using stimulated photoacoustic Raman spectroscopy. A complete assignment was carried out with the aid of quantum chemistry calculations and depolarization ratio measurement as well as isotope substitutions, i.e. CH 3 CD 2 CD 2 OH, CD 3 CH 2 CD 2 OH and CD 3 CD 2 CH 2 OH. It is shown that the spectra of three C―H groups of n‐propanol overlap each other because of Fermi resonance coupling and different molecular conformations, leading to complex features that were not determined previously. In addition, the comparisons between the spectra of three isotopologues reveal that the C―H vibrations at different sites of carbon chain exhibit different sensitivity to conformational change of n‐propanol. The CH 3 stretching vibration at terminated γ‐carbon is not sensitive whereas the CH 2 stretching vibrations at both α‐carbon and β‐carbon atoms are sensitive. Furthermore, Raman spectra of liquid propanol recorded by conventional spontaneous Raman technique are reassigned on the basis of gas‐phase analysis. Copyright © 2016 John Wiley & Sons, Ltd.