First analysis of the high resolution FTIR spectrum of the ν2 band of the FCO2 radical at 970.2 cm−1

Abstract

The infrared spectrum of the fluorocarboxyl radical, FCO2, was recorded at high resolution (0.0035 cm−1) in the 600–1400 cm−1 region on a Bruker IFS 120 HR Fourier transform spectrometer of the University of Wuppertal. The analysis of the A-type ν2 band of FCO2 (CF stretching mode) centred at 970.208 cm−1 was performed making use of the ground state parameters achieved by [L. Kolesniková, J. Varga, H. Beckers, M. Šimečková, Z. Zelinger, L. Nová Stříteská, P. Kania, H. Willner, and Š. Urban, J. Chem. Phys. 128, 224302/1 (2008)]. For the FCO2 radical, the ν2 transitions are, in principle, split into two spin–rotation subcomponents corresponding to J = N ±1/2. However the spin–rotation parameters in the 21 vibrational state have values similar to those of the ground state, and spin–rotation doublings are observable only for the weaker transitions involving medium Ka or Kc values in the P and R branches. The ν2 fundamental band is weakly perturbed by the 2ν5 dark overtone band at 965.4 cm−1 and the 21 and 52 energy levels of FCO2 are coupled through Fermi type resonances. The final energy level calculation was performed accounting both for the spin–rotation interaction within the 21 and 52 vibrational states, and the 21 ⇔ 52 Fermi-type resonances.