ELECTRONIC-SPECTRA OF 1-CYANO-4-METHYLNAPHTHALENE AND ITS CLUSTERS IN A SUPERSONIC FREE JET EXPANSION

The fluorescence excitation and dispersed fluorescence spectra of the monomer, dimer, and trimer of 1-cyano-4-methylnaphthalene (4-MCNN) were measured in a supersonic free jet. It was found that the molecule easily forms the dimer and trimer. These clusters seem to have fairly rigid structures stabilized by dipole-dipole interaction and do not form the excimer in the excited state. The results explain the observation by Itoh et al. that the excimer formation occurs only for the clusters of n > 3. The intramolecular vibrational redistribution and vibrational predissociation were also observed for the vibronic levels of the dimer.