LASER INDUCED FLUORESCENCE EXCITATION SPECTRA OF 1-FLUORO, 1-CHLORO, AND 1-BROMONAPHTHALENE IN A SUPERSONIC $JET^{1}$

Author Institution: Department of Chemistry, University of PittsburghThe 1-halonaphthalenes have played a central role in the development of our understanding of the role of spin-orbit coupling in photo-physical processes [e. g., intersystem crossing (ISC)] in the condensed phase. In this work, we examine the interesting possibility that more detailed information about the dynamics of such processes can be obtained from experiments on the isolated molecule. Toward this end, we have obtained vibronically resolved laser induced fluorescence excitation spectra of 1-fluoronaphthalene (1FN), 1-chloronaphthalene (1CN), and 1-bromonaphthalene (1BN) in seeded supersonic jets of helium, and compared the results with those of similar experiments on the parent $molecule.^{2,3}$ Preliminary assignments of these rather complex spectra will be given, and further experiments designed to uncover possible mode specificities in the ISC process will be described. $^{1}$Work supported by The National Science Foundation. $^{2}$S. M. Beck, D. E. Powers, J. B. Hopkins, and R. E. Smalley, J. Chem. Phys. 73, 2019 (1980). $^{3}$F. M. Behlen and S. A. Rice, J. Chem. Phys, 75, 5672 (1981