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Dimer and Trimer in Pyridine–Ethanol Mixture Reinvestigated Applying the Scanning Multi‐Channel Raman Difference Technique and AM1 Molecular Orbital Calculations
Author(s) -
Deckert V.,
Asthana B. P.,
Mishra P. C.,
Kiefer W.
Publication year - 1996
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/(sici)1097-4555(199612)27:12<907::aid-jrs52>3.0.co;2-#
Subject(s) - trimer , chemistry , dimer , raman spectroscopy , pyridine , analytical chemistry (journal) , molecule , laser linewidth , molecular orbital , optics , organic chemistry , physics , laser
High‐precision measurements on the ν 1 (ring‐breathing) mode in pyridine–ethanol mixtures with varying mole fraction of the reference molecule pyridine were made using a device for multi‐channel and scanning multi‐channel Raman difference spectroscopy (SMT‐RDS) with CCD detection developed recently in this laboratory. The high quality of the data permits one to make precise estimates of wavenumber shifts, linewidth (FWHM) changes and integrated intensities. The spectral features observed in the range 970–1010 cm −1 in mixtures having different molar ratios of C 5 H 5 N and C 2 H 5 OH were assigned to ‘free’ C 5 H 5 N, dimer [C 5 H 5 N···(HOC 2 H 5 )] and trimer [C 5 H 5 N···(HOC 2 H 5 ) 2 ]. These three species co‐exist in the mixture along with the solvent in concentration‐dependent ratios. Geometry optimization and vibrational frequency calculations performed using the AM1 molecular orbital method were used to interpret the experimental observations.