title: C6H and C6D: electronic spectra and Renner-Teller analysis.
abstract: Rotationally resolved spectra of the B(2)Π - X(2)Π 0(0)(0) electronic origin bands and 11(1)(1) μ(2)Σ-μ(2)Σ vibronic hot band transitions of both C(6)H and C(6)D have been recorded in direct absorption by cavity ring-down spectroscopy through a supersonically expanding planar plasma. For both origin and hot bands accurate spectroscopic parameters are derived from a precise rotational analysis. The origin band measurements extend earlier work and the 11(1)(1) μ(2)Σ-μ(2)Σ vibronic hot bands are discussed here for the first time. The Renner-Teller effect for the lowest bending mode ν(11) is analyzed, yielding the Renner parameters ε(11), vibrational frequencies ω(11), and the true spin-orbit coupling constants A(SO) for both (2)Π electronic states. From the Renner-Teller analysis and spectral intensity measurements as a function of plasma jet temperature, the excitation energy of the lowest-lying 11(1) μ(2)Σ vibronic state of C(6)H is determined to be (11.0 ± 0.8) cm(-1).
authors.affiliation: Institute for Lasers, Life, and Biophotonics, VU University Amsterdam, De Boelelaan 1081, NL 1081HV Amsterdam, The Netherlands. d.zhao@vu.nl
authors.forename: Dongfeng
authors.initials: D
authors.lastname: Zhao
authors.forename: Mohammad Ali
authors.initials: MA
authors.lastname: Haddad
authors.forename: Harold
authors.initials: H
authors.lastname: Linnartz
authors.forename: Wim
authors.initials: W
authors.lastname: Ubachs
mesh_terms: D004583:Electrons; D005118:Extraterrestrial Environment / Q000737:chemistry*; D006838:Hydrocarbons / Q000737:chemistry*; D008956:Models, Chemical; D011789:Quantum Theory; D013057:Spectrum Analysis / Q000379:methods
chemical_list: D006838:Hydrocarbons