title: Infrared spectroscopy of the helium solvated cyclopentadienyl radical in the CH stretch region.
abstract: Cyclopentadienyl radicals were produced by vacuum flash pyrolysis and trapped in superfluid helium nanodroplets. The infrared spectrum of the embedded radicals was recorded in the range 3020-3120 cm(-1). Three bands observed at 3056.3, 3086.9, and 3117.3 cm(-1) were assigned to the transitions from the ground state to the three levels of the quadratically Jahn-Teller distorted (i.e., second order Jahn-Teller active) CH stretch vibration with E1' symmetry. Accompanying ab initio calculations showed a vibrationally averaged symmetric equilibrium structure in agreement with the observed vibronic transitions. Our results confirm a symmetric configuration of the cyclopentadienyl (cp) radical that is dynamically Jahn-Teller distorted. Density functional theory calculations and infrared data further suggest that barrier-less reactions of two cp radicals occur within the droplets.
authors.affiliation: Department of Chemistry and Biochemistry, Ruhr-Universität Bochum, Bochum, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Leicht
authors.affiliation: Department of Chemistry and Biochemistry, Ruhr-Universität Bochum, Bochum, Germany.
authors.forename: Matin
authors.initials: M
authors.lastname: Kaufmann
authors.affiliation: Department of Chemistry and Biochemistry, Ruhr-Universität Bochum, Bochum, Germany.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Schwaab
authors.affiliation: Department of Chemistry and Biochemistry, Ruhr-Universität Bochum, Bochum, Germany.
authors.forename: Martina
authors.initials: M
authors.lastname: Havenith