HIGH-RESOLUTION INFRARED AND RAMAN SPECTROSCOPY OF SF$_6$: THE STATE-OF-THE-ART IN JUNE 2006

Abstract

Sulfur hexafluoride is recognized by the Kyoto Protocol as a powerful greenhouse gas whose emissions should be monitored and reduced. Although its abundance is still relatively small ($3.8\times 10^{-6}$ ppmv), it is increasing rapidly ($8$ \%$/$year) while the lifetime of SF$_6$ in the atmosphere is extremely long ($3200$ years) with a Global Warming Potential equal to 23900 compared to CO$_2$} {\bf 24}, 675--678 (1997).}$^,$}. It is thus necessary to correctly model the atmospheric absorption of SF$_6$} (2006).}, especially in the strongly absorbing $\nu_3$ region (near $939$ cm$^{-1}$). Until recently, however, respective spectra were not very well known. In particular, the knowledge of hot bands is very important for atmospheric applications, but this implies to study various vibrational levels, some being only accessible through Raman scattering. During the past decade, we have analyzed different fundamental, harmonic and combination bands for both ${}^{32}$SF$_6$ and ${}^{34}$SF$_6$ using high-resolution infrared and Raman spectra} {\bf 222}, 291--295 (2003), V. Boudon, J. L. Domenech, D. Bermejo and H. Willner, {\em J. Mol. Spectrosc.\/} {\bf 228}, 392--400 (2004) and references therein.}. In this talk, we will discuss the present status and prospects of SF$_6$ spectroscopy. In particular, new spectra and analyses of ${}^{34}$SF$_6$ will be reported and discussed. We will also show that a correct modelling of absorption intensities is still a pending question.