title: Communication: Evidence for dipole-bound excited states in gas-phase I(-) ⋅ MI (M = Na, K, Cs) anionic salt microclusters.
abstract: We report the first UV laser photodissociation spectra of gas-phase I(-) ⋅ MI (M = Na, K, Cs) alkali halide anionic microclusters. The photodepletion spectra of these clusters display strong absorption bands just below the calculated vertical detachment energies, indicative of the presence of dipole-bound excited states. Photoexcitation at the peak of the transition to the dipole-bound excited state results in production of a primary [MI](-) photofragment along with a less intense I(-) ion. The photofragmentation mechanism of the excited state cluster is discussed in the context of an initial dipole-bound excited state that subsequently relaxes via a vibrational Feschbach resonance. The experiments described have been performed in an electrospray source laser-interfaced quadrupole ion-trap instrument and demonstrated for the first time that dipole-bound excited states can be identified in the relatively high-collision environment of a quadrupole ion-trap, in particular for systems with large dipole moments associated with the presence of charge separation. This indicates considerable potential for future experiments that identify dipole-bound excited states as a "low-resolution" structural probe of biomolecules and molecular charge separation using the instrumentation employed in this work.
authors.affiliation: Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom.
authors.forename: Andrew J A
authors.initials: AJ
authors.lastname: Harvey
authors.affiliation: Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom.
authors.forename: Naruo
authors.initials: N
authors.lastname: Yoshikawa
authors.affiliation: Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom.
authors.forename: Jin-Guo
authors.initials: JG
authors.lastname: Wang
authors.affiliation: Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom.
authors.forename: Caroline E H
authors.initials: CE
authors.lastname: Dessent