TORSIONAL VIBRATIONS IN JET-COOLED 1.8-DIMETHYLNAPHTHALENE.

Author Institution: Chemistry Depatment, Rutgers UniversityMethyl group internal rotation transitions involving the $a_{2}$ torsion in 1,8-dimethylnaphthalene and $-d_{6}$ (methyl deuteriums) isotopomer are reported for the ground and first $L_{b} (^{1}B_{2u})$ excited state from laser induced jet cooled fluorescence excitation and single vibronic fluorescence spectra. The torsional frequencies are employed to generate potential functions for both states and compared with those obtained from abinitio and semiempirical calculations