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High Resolution Electronic Spectroscopy of Molecular Conformers. Methyl‐3‐methoxybenzoic Acid Ester
Author(s) -
Ribblett Jason W.,
Sinclair Wayne E.,
Pratt David W.
Publication year - 1997
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.199700045
Subject(s) - conformational isomerism , chemistry , spectroscopy , electronic structure , crystallography , computational chemistry , molecular physics , molecule , physics , organic chemistry , quantum mechanics
By combining the techniques of rotationally resolved fluorescence excitation spectroscopy in molecular beams and ab initio quantum mechanics, we have determined the identity of the four conformers that contribute to the S 1 ←S 0 electronic spectrum of methyl‐3‐methoxybenzoic acid ester in the gas phase. Each conformer exhibits a unique spectrum. Each conformer also exhibits a differently oriented electronic transition moment (TM) in the molecular frame, for which the distinguishable inertial and electronic contributions also have been determined. The results suggest that the S 1 ←S 0 TM vectors of all conformers are rotated by relatively large (counterclockwise) angles with respect to the a inertial axes, placing them close to the b axis of a —OCH 3 substituted benzene, and that the exact values of these angles depend upon the mutual conformations of both attached groups with respect to each other.