Communication: Evidence for dipole-bound excited states in gas-phase I- · MI (M = Na, K, Cs) anionic salt microclusters

TY - JOUR

T1 - Communication

T2 - Evidence for dipole-bound excited states in gas-phase I- · MI (M = Na, K, Cs) anionic salt microclusters

AU - Harvey, Andrew J A

AU - Yoshikawa, Naruo

AU - Wang, Jin Guo

AU - Dessent, Caroline E H

N1 - © 2015 AIP Publishing LLC.

PY - 2015/9/14

Y1 - 2015/9/14

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=84941910374&partnerID=8YFLogxK

U2 - 10.1063/1.4930919

DO - 10.1063/1.4930919

M3 - Article

AN - SCOPUS:84941910374

SN - 0021-9606

VL - 143

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

IS - 10

M1 - 101103

ER -