title: The complex spectrum of a "simple" free radical: the Ã-X̃ band system of the jet-cooled boron difluoride free radical.
abstract: The near-ultraviolet band system of the jet-cooled boron difluoride free radical has been studied by a combination of laser-induced fluorescence and single vibronic level wavelength resolved emission spectroscopies. The radical was produced in a supersonic discharge jet using a precursor mixture of 1%-3% of BF(3) or (10)BF(3) in high pressure argon. A large number of bands were found in the 340-286 nm region and assigned as transitions from the X̃(2)A(1) ground state to the lower Renner-Teller component of the Ã(2)Π excited state, based on our previous ab initio potential energy surface predictions, matching the emission spectra Franck-Condon profiles of (11)BF(2) and (10)BF(2), and comparison of observed and calculated boron isotope effects. Several bands have been rotationally analyzed providing ground state structural parameters of r(0)('') (BF) = 1.3102(9) Å and θ(0)('') (FBF) = 119.7(6)°. The ground state totally symmetric vibrational energy levels of both boron isotopologues have also been measured and assigned up to energies of more than 8000 cm(-1). Although BF(2) might be considered to be a "simple" free radical, understanding the details of its electronic spectrum remains a major challenge for both theory and experiment.
authors.affiliation: Institute of Modern Physics, The Chinese Academy of Sciences, Lanzhou, Gansu 730000, People's Republic of China.
authors.forename: Jie
authors.initials: J
authors.lastname: Yang
authors.forename: Blaine
authors.initials: B
authors.lastname: Ellis
authors.forename: Dennis J
authors.initials: DJ
authors.lastname: Clouthier