Electronic Structure of BCl Determined by Ab Initio Calculations and Resonance-Enhanced Multiphoton Ionization Spectroscopy

Abstract

We report the first electronic absorption spectrum of the boron difluoride radical. This spectrum appeared in mass-selected multiphoton ionization spectra between 235 and 420 nm. Strong bent−linear structure changes prevented observations of electronic origin bands. EOM-CCSD ab initio calculations suggest that the observed vibrational bands arise from A2B1 ← X 2A1 (Tvert = 35 100 cm-1) one-photon absorption and from B 2A1 (3s) ←← X 2A1 (Tvert = 59 100 cm-1) and C (3p) ←← X 2A1 (Tvert = 63 100 cm-1) two-photon transitions. Ab initio calculations predicted the geometries and vibrational frequencies of the ground states of the BF2 radical, cation, and anion. Ab initio calculations also predicted the vertical transition energies to the excited electronic states from the ground state radical. QCISD(T) calculations estimate ionization potentials for BF2 radicals of IPa = 8.66 eV and IPv = 10.44 eV and adiabatic and vertical electron detachment energies for BF2- of EA = 1.14 eV and VDE = 1.64 eV. We estimat...