An energy denominator study of the phonon side band in isotopic mixed naphthalene crystals

The fluorescence phonon sidebands of C10H8 and 1,4,5,8-C10D4H4 guests in C10H8 are studied and compared at 2 K. The mild differences are attributed to the increased delocalization of the C10D4H4 1B2u electronic state. The relative importance of the diagonal (Franck-Condon) versus off-diagonal (Herzberg-Teller) electron-phonon coupling terms is discussed. We also demonstrate that the dispersion force coupling (and not the resonance force coupling) dominates the 1B2u (and 3B1u) C10H8 in C10D8 phonon sideband structure, and is responsible for its intensity distribution (and the difference therein between fluorescence and phosphorescence).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22232/1/0000666.pd