Assignment of the {tilde B}{sup +} state of the chlorobenzene cation using photoinduced Rydberg ionization (PIRI) spectroscopy
The photoinduced Rydberg ionization (PIRI) spectra of the {tilde B}{sup +} state of the chlorobenzene cation were recorded via the origin, 6b, and 16a16b vibrations of the cation ground state ({tilde X}{sup +}). The resonance-enhanced multi photon dissociation spectroscopy (REMPD) spectrum of the {tilde B}{sup +} {l{underscore}arrow} {tilde X}{sup +} transition of the chlorobenzene cation was also obtained. To date it has been thought that {tilde B}{sup +} {l{underscore}arrow} X{sup +} is an electronically forbidden transition (C{sub 2{nu}} symmetry), taking place from the {sup 2}B{sub 1} ground state to a {sup 2}B{sub 2} excited state. The ability of PIRI to provide spectra from specific lower-state vibrational levels allowed this hypothesis to be tested, because the 16a vibration would be the primary inducing mode in the transition. Assuming a forbidden transition, a comparison between the spectrum from the ground-state origin and that from the 16a16b vibration would necessitate an assignment that gives unlikely vibrational frequencies. It is therefore concluded that the {tilde B}{sup +} {l{underscore}arrow} {tilde X}{sup +} transition of chlorobenzene is electronically allowed. Configuration interaction of singles (CIS) and complete active space multiconfigurational self-consistent field (CASSCF) calculations with 6-31G** basis sets were performed to ascertain the symmetry assignments of the excited ionic states. These calculations resulted in the possibility that at least one excited state of the cation of {sup 2}B{sub 1} symmetry lies below any state of {sup 2}B{sub 2} symmetry. Hence, the authors propose that the ionic transition observed in the acquired PIRI/REMPD spectra of the cation is an allowed transition to a {sup 2}B{sub 1} state, thus giving rise to the observation of the origin of the {tilde B}{sup +} state at 18,219 cm{sup {minus}1}.
- Research Organization:
- State Univ. of New York, Stony Brook, NY (US)
- Sponsoring Organization:
- US Department of Energy
- OSTI ID:
- 20003224
- Journal Information:
- Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory, Journal Name: Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory Journal Issue: 45 Vol. 103; ISSN JPCAFH
- Country of Publication:
- United States
- Language:
- English
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