Accurate dissociation energies were determined for gas-phase complexes between 1-naphthol and benzene, d₆-benzene and cyclohexane, using the stimulated emission pumping resonant two-photon ionization spectroscopy technique in supersonic jets. The dissociation energies obtained for the electronic ground state are surprisingly large being D₀ = 5.07±0.07 kcal/mol for 1-naphthol · benzene, 5.08±0.06 kcal/mol for 1-naphthol · d₆-benzene, and 6.92±0.03 kcal/mol for 1-naphthol · cyclohexane, respectively. The dissociation energies scale well with the parallel molecular polarizabilities.

Massâ€�selective groundâ€�state vibrational spectra of jetâ€�cooled carbazoleâ‹…R (R=Ne, Ar, Kr, and Xe) van der Waals complexes were obtained by populating groundâ€�state intraâ€� and intermolecular levels via stimulated emission pumping, followed by time delayed resonant twoâ€�photon ionization of the vibrationally hot complex. By tuning the dump laser frequency, S₀ state vibrational modes were accessed from ≊200 cm^−1 up to the dissociation energy D₀. Upon dumping to groundâ€�state levels above D₀, efficient vibrational predissociation of the complexes occurred, allowing us to determine the S₀ state van der Waals binding energies very accurately. The D₀(S₀) values are <214.5±0.5 cm^−1 (R=Ne), 530.4±1.5 cm^−1 (R=Ar), 687.9±4.0 cm^−1 (R=Kr), and 890.8±1.6 cm^−1 (R=Xe). In the S₁ state, the corresponding binding energies are larger by 9% to 12%, being <222.9±1.0 cm^−1, 576.3±1.6 cm^−1, 756.4±4.5 cm^−1, and 995.8±2.5 cm^−1, respectively.

Massâ€�selective groundâ€�state vibronic spectra of molecular van der Waals complexes carbazoleâ‹…S, S=N₂, CO, and CH₄, were measured by stimulated emission pumping followed by resonant twoâ€�photon ionization of the vibrationally hot complexes. S₀â€�state vibrational modes were accessed from ≊200 cm^−1 up to the groundâ€�state dissociation limit D₀(S₀) of the van der Waals bond. Above D₀, 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 N₂, 716.5±29.8 cm^−1 for CO, and 668.6±15.1 cm^−1 for CH₄. In the S₁ 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 N₂ and CH₄, similar to the analogous rare gases Ar and Kr. For CO, the relative increase of van der Waals binding energy is 23%. The differences are primarily due to electrostatic interactions.

Accurate hydrogen-bond dissociation energies were determined for gas-phase hydrogen-bonded complexes between 1-naphthol or 1-naphthol-d₃ and H₂O, CH₃OH, NH₃ and ND₃, using the stimulated emission pumping-resonant two-photon ionization spectroscopy technique in supersonic jets. The hydrogen-bond dissociation energies obtained for the electronic ground state are D₀ = 2035 ± 69 cm^−1 for 1-naphthol · H₂O, 2645 ± 136 cm^−1 for 1-naphthol · CH₃OH, 2680 ± 5cm ^−1 for 1-naphthol · NH₃ and 2801 ± 14 cm^−1 for 1-naphthol-d₃ · ND₃, respectively. Upon electronic excitation to the S₁ state the binding energies increase by approximately 8%.

Mass-selective ground state vibrational spectroscopy of the jet-cooled carbazole·Ar complex was performed by populating ground-state levels via a pump/dump laser pulse sequence, followed by selective resonant two-photon ionization of the vibrationally relaxed complexes. Intra- and inter-molecular van der Waals modes in the S₀ state are measurable with good signal/noise. The ground-state binding energy can be determined by detecting the negative signals resulting from loss of ground-state population via vibrational predissociation of the complex.