Knowledge Bank

Rotationally resolved fluorescence excitation spectra of the origin bands in the $S1\leftarrow S0$ transitions of each of the four conformers of methyl-3-hydroxybenzoate and its deuterated isotopomer have been recorded. The different origins have been assigned to individual conformers associated with the cis and trans configurations of the OH(D) substituent and the cis and trans configurations of the ester substituent using Kraitchman's equations. Spectra of methyl- and ethyl-3-aminobenzoate also have been recorded and analyzed to provide assignments based on their inertial parameters. Further analysis provides a determination of the absolute orientations of the transition moments in the molecular frame of each of the conformers and their dependence upon both the inertial and electronic properties of the substituent.