Journal of Chemical Physics, Vol.103, No.17, 7228-7239, 1995
Binding-Energies of Carbazole-Center-Dot-S Van-der-Waals Complexes (S=n-2, Co, and CH4)
Mass-selective ground-state vibronic spectra of molecular van der Waals complexes carbazole S, S=N-2, CO, and CH4, were measured by stimulated emission pumping followed by resonant two-photon ionization of the vibrationally hot complexes. S-0-state vibrational modes were accessed from approximate to 200 cm(-1) up to the ground-state dissociation limit D-0(S-0) of the van der Waals bond. Above D-0, efficient vibrational predissociation of the complexes occurs, allowing accurate determination of the van der Waals dissociation energies as 627.2+/-7.9 cm(-1) for N-2, 716.5+/-29.8 cm(-1) for CO, and 668.6+/-15.1 cm(-1) for CH4. In the S-1 excited state, the van der Waals binding energies increase to 678.5+/-8.0, 879.2+/-29.9, and 753.8+/-15.2 cm(-1), respectively. The relative increases upon electronic excitation are about 8% and 13% for N-2 and CH4, Similar to the analogous rare gases Ar and Rr. For CO, the relative increase of van der Waals binding energy is 23%. The differences are primarily due to electrostatic interactions.
Keywords:INTRAMOLECULAR VIBRATIONAL-RELAXATION;THRESHOLD IONIZATION SPECTROSCOPY;STIMULATED-EMISSION SPECTROSCOPY;FLUORESCENCE SPECTROSCOPY;VANDERWAALS MOLECULES;PARA-DIFLUOROBENZENE;ANISOLE.AR COMPLEX;METHANE;CLUSTERS;DYNAMICS