VUV photoabsorption in CF3X (X = 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.