A photoelectron spectroscopic study of the second ionisation of the CF(X-2Pi) radical

The CF(X(2)Pi) radical has been re-investigated with vacuum ultraviolet pho toelectron spectroscopy. Two bands were observed and assigned to the ionisa tions CF+(X(1)Sigma (+))<-- CF(X(2)Pi) and CF+(a(3)Pi)<-- CF(X(2)Pi). The f irst band, which has been observed previously, has an adiabatic ionisation energy of (9.11 +/-0.02) eV and a vertical ionisation energy of (9.55 +/-0. 02) eV. For the second band, three vibrational components were observed wit h the first, the most intense, at an ionisation energy of (13.94 +/-0.02) e V. Analysis of the vibrational structure in the two observed bands allowed omega (c) and r(c) to be determined as 1810 +/- 30 cm(-1) and 1.154 +/-0.00 5 Angstrom, respectively for the first ionic state, CF+(X(1)Sigma (-)), and 1614 +/- 30 cm(-1) and 1.213 +/-0.005 Angstrom, respectively for the secon d ionic state, CF+(a(3)Pi). Comparison of the ionisation energies and spect roscopic constants obtained has been made with values obtained from recent multi-reference configuration interaction calculations. (C) 2001 Elsevier S cience B.V. All rights reserved.