State-Selective Analysis of Ground-State Vibrational Predissociation Product of an Aromatic van der Waals Complex

摘要

The method previously presented for mass-selective ground-state vibrational spectroscopy of aromatic van der Waals complexes by populating ground-state levels via a pump/dump laser pulse sequence, followed by selective resonant two-photon ionization (R2PI) of the vibrationally relaxed complexes [T. Buergi et al., Chem. Phys. Lett., 225, 351 (1994)] is here extended to the detection of the aromatic molecular product from the S_0 state vibrational predissociation (VP) process. Schemes and results are presented which allow (a) extended measurements of intra-and intermolecular vibrational frequencies of carbazole · Ar in the S_0 state, (b) detection of vibrationally hot, but rotationally cold carbazole VP product, and (c) vibrationally and rotationally hot carbazole VP products. A much improved determination of the van der Waals dissociation energy was made by combining results from various experiments, as D_0(S_0) = 530 ± 1.5 cm~(-1).