title: Gas phase electronic spectrum of linear AlCCH.
abstract: The electronic spectrum of the aluminium containing species AlCCH has been detected in the gas phase in the region 315-355 nm. The experiment used a mass selective resonant two-color two-photon ionization technique coupled to a laser ablation source. Structures of the AlCCH isomers have been optimized using density functional theory (DFT) and the excitation energies to the low-lying electronic excited states calculated. Based on the analysis of the observed rotational structure and the theoretical data, the spectrum is assigned to the A (1)Pi<-- X (1)Sigma(+) electronic transition of linear AlCCH. The vibronic band system is complicated by the Renner-Teller effect in the excited state. The assignment yields nu(4)'' = 516.4 cm(-1) for the stretching mode in the ground X (1)Sigma(+) state and nu(4)' = 654.5 cm(-1) for A (1)Pi excited state. Molecular constants determined from the rotational analysis are B(0)'' = 0.16487(14), B(0)' = 0.17845(13) and T(0) = 28 755.04 cm(-1). The experimental and theoretical data indicate a shorter Al-C bond in the A (1)Pi excited than the X (1)Sigma(+) ground state.
authors.affiliation: Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland.
authors.forename: Cristina
authors.initials: C
authors.lastname: Apetrei
authors.forename: Hongbin
authors.initials: H
authors.lastname: Ding
authors.forename: John P
authors.initials: JP
authors.lastname: Maier
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D000535:Aluminum / Q000737:chemistry*; D004583:Electrons; D005740:Gases; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D044367:Phase Transition; D014732:Vibration
chemical_list: D000480:Alkynes; D005740:Gases; D009942:Organometallic Compounds; D000535:Aluminum