title: Gas phase electronic spectrum of T-shaped AlC2 radical.
abstract: Gas phase electronic transitions for the C 2B2<--X 2A1 and D 2B1<--X 2A1 band systems of T-shaped AlC2 (C2v) radical have been measured in the 345-475 nm range. Vibrational analyses of both band systems are reported. Simulation of several rotationally resolved bands confirms previously obtained rotational parameters for the C 2B2 state. The radical is produced by ablating an aluminum rod in the presence of acetylene gas. The resulting supersonic molecular beam is probed using both mass-selective resonant two-color two-photon ionization and laser induced fluorescence. Ab initio calculations and vertical electronic excitation energies help the assignment. Vibrational frequencies for the X 2A1, C 2B2, and D 2B1 states have been determined. Rotational analysis of a number of bands yields spectroscopic constants for one vibronic state in the C 2B2 manifold and the origin band of the D 2B1<--X 2A1 system.
authors.affiliation: Department of Chemistry, University of Basel, Klingelbergstr. 80, CH-4056 Basel, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Apetrei
authors.forename: A E W
authors.initials: AE
authors.lastname: Knight
authors.forename: E
authors.initials: E
authors.lastname: Chasovskikh
authors.forename: E B
authors.initials: EB
authors.lastname: Jochnowitz
authors.forename: H
authors.initials: H
authors.lastname: Ding
authors.forename: J P
authors.initials: JP
authors.lastname: Maier