Vibrational predissociation dynamics in the vibronic states of the aniline-neon van der Waals complex: New features revealed by complementary spectroscopic approaches

We report two independent sets of experimental spectroscopic data which bot h contain information about the vibrational dynamics occurring in the anili ne-neon van der Waals complex in its S-1 electronically excited state. The high resolution excitation spectra of the three vibronic bands, <(6a(0)(1)) over bar>, <(I-0(2))over bar>, and <(1(0)(1))over bar>, of the S-1 <-- S-0 transition, exhibit lifetime broadening with respect to transitions to the corresponding states in the aniline monomer. The dispersed emission spectra taken under excitation of the same three vibronic bands give access to bot h the distribution of aniline monomer states produced by vibrational predis sociation of the complex and to the rates at which this dynamics proceeds. The overall results are discussed in a consistent way, with emphasis being given to the role of the coupling between the intramolecular and the interm olecular vibrational states. In the case of <(I-0(2))over bar> excitation, it is shown that this coupling is reflected in the shape of the van der Waa ls wavefunction, as accessed through the analysis of the high resolution sp ectra [M. Becucci, G. Pietraperzia, N. M. Lakin, E. Castellucci, Ph. Brechi gnac, Chem. Phys. Lett. 260, 87 (1996).]. (C) 1999 American Institute of Ph ysics. [S0021-9606(99)01020-X].