High resolution electronic spectroscopy of molecular conformers. Methyl- and ethyl-3-aminobenzoic acid esters

Rotationally resolved fluorescence excitation spectra of the S1 ⌉ S0 origin bands of two conformers of methyl-3-amino-benzoate and four conformers of ethyl-3-aminobenzoate have been obtained. Analyses of these spectra yield the rotational constants of each conformer in the two electronic states and the polarizations of all six bands in the inertial reference frame. Comparison of the results for the different conformers leads to an unambiguous assignment of specific bands to specific conformers and to an improved understanding of the factors that influence the S1 ⌉ S0 transition moment alignments in these and other substituted aromatic molecules.