VUV photoabsorption in CF3X (XÂ =Â Cl, Br, I) fluoro-alkanes

A new ultraviolet beam line has been constructed at the Institute of Storage Rings, University of Aarhus (ISA) to study the Photoabsorption of aeronomic molecules. In this paper, visible-UV spectra of CF3Cl and CF3Br are reported at high-resolution in the energy range 3.9-10.8 eV (320-115 nm). For both molecules, the present work provides the most reliable absolute cross-sections available at energies above the lowest lying electronic transition, the dissociative A band. Results are compared with earlier data including the recently published photoabsorption spectrum of CF3I [N.J. Mason, P. Limão-Vieira, S. Eden, P. Kendall, S. Pathak, A. Dawes, J. Tennyson, P. Tegeder, M. Kitajima, M. Okamoto, K. Sunohara, H. Tanaka, H. Cho, S. Samukawa, S.V. Hoffmann, D. Newnham, S.M. Spyrou, Int. J. Mass Spectrom. 223-224 (2003) 647]. The CF3I spectrum is revisited and new assignments made, including the extension of previously proposed ns Rydberg series. A detailed description of the ASTRID photoabsorption apparatus at ISA is provided for the first time.