Action spectrum acquired by scanning the pump laser throughout the ICl , 15–0 region (a) and the ICl , 2–0 region (b) with the probe laser fixed to detect the vibrational predissociation or collisional relaxation products. The spectra are plotted relative to the respective monomer band origins. The higher-energy satellite features are associated with transitions of the T-shaped and linear, ground-state van der Waals complexes to different excited-state intermolecular vibrational levels.
Two-photon spectra recorded in the ICl , 11–2 and , 1–15 regions. The spectra were acquired with the pump laser fixed on a or feature and scanning the probe laser. The spectra in (a) and (b) were acquired by pumping the T-shaped ground-state complexes to the lowest-lying level in the excited state, . The spectra in (c) and (d) were acquired by pumping linear, ground-state complexes to a delocalized level in the intermediate state, . The features are labeled with the assigned intermolecular bending and stretching levels of the complexes that are accessed in the ion-pair states. The asterisks denote either vibrational predissociation or direct dissociation products that are excited to ion-pair states.
Two-photon spectra recorded by exciting van der Waals complexes in the , 0–15, 1–15, and 2–15 regions and plotted as a function of the shift from the , 0–15, 1–15, and 2–15 monomer band origins at , , and , respectively (Refs. 23–25). The spectra in (a) were recorded by pumping the T-shaped , 15–0 feature at and are normalized so that the intensities of the features at are the same. The two spectra in (b) were acquired by pumping the linear , 15–0 feature at . These spectra are normalized so that the intensities of the features at are the same. The intermolecular bending and stretching levels accessed in the ion-pair states are labeled .
The energy-level diagram of the levels accessed in order to determine the binding energy of the T-shaped conformer. The pump lasers were fixed to prepare the indicated levels via transitions in the ICl , 3–0 region, and the probe lasers accessed the level in the ion-pair state associated with the potential. The binding energy of the linear conformer has been measured to be (Ref. 17).
Energy-level diagram illustrating the intermolecular bending and stretching levels bound within the potentials. The energies of the and states (Ref. 24) shift to above and below the energy of the lowest-lying (0,0) level of the complex with increasing . The changing nonadiabatic dynamics between these states results in the observed dependence of the intensity of the (0,0) feature on .
Transition energies (in ) of the discrete features observed in LIF spectra recorded in consecutive ICl , regions. Each energy corresponds to that of the peak intensity for each feature.
Energies of the discrete intermolecular levels accessed in this work. The and labels represent intermolecular bending and stretching levels, respectively. (Assignment of the and labels assumes local intermolecular vibrational modes within the complex.) All values are reported in units of wavenumbers, , and are relative to the corresponding asymptote.
Experimental and theoretical binding energies (in ) for van der Waals complexes in different electronic states with the indicated ICl vibrational excitation.
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