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Vibrational dephasing in polar molecular liquids: An application to a fundamental and its overtone in phenyl acetylene
Author(s) -
Baglin Frank Geile
Publication year - 1980
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.1250090315
Subject(s) - dephasing , chemistry , overtone , acetylene , dilution , delocalized electron , polar , raman spectroscopy , relaxation (psychology) , solvent , analytical chemistry (journal) , quadrupole , phase (matter) , nuclear magnetic resonance , thermodynamics , atomic physics , organic chemistry , condensed matter physics , spectral line , physics , psychology , social psychology , astronomy , optics
Based upon the results reported here for phenyl acetylene and the results of other investigators' studies, a working model of phase relaxation in polar molecular liquids is proposed. The model rests upon the established concept of a phase annihilation operator 1 and a postulated phase conduction band structure for polar molecular liquids. Three cases are discussed; briefly, they are (I) no effect upon the signal of interest by dilution, (II) narrowing of the signal of interest by dilution, and (III) broadening of the signal of interest by dilution. The latest effect has not been elucidated previously in the literature. Actual examples of each of these cases are discussed. Phenyl acetylene's v cc and 2 v cc modes are shown to display Case II behavior. These two modes are found in the Raman spectrum at 2113 cm −1 ( v cc ) and 4205 cm −1 (2 v cc ). They have been examined by varying the concentration of this molecule in two dipolar solvents, a quadrupolar solvent and an octopolar solvent. In addition, temperature studies on the neat sample were carried out at 10–30 K intervals for v cc and at 275 K and 90 K for 2 v cc . From the results of our investigation, a relaxation mechanism consistent with a quadrupole–quadrupole dephasing type mechanism is postulated for both v cc and 2 v cc .