Sulfur hexafluoride detection by Radar resonance enhanced multiphoton ionization

In this study, we have demonstrated the stand-off detection of sulfur hexafluoride by the Radar resonance multi-photon ionization process. In order to obtain a well defined spectral signature, the sulfur hexafluoride molecules are first dissociated by a focused pulsed Nd:YAG laser to sulfur difluoride molecules, which are then ionized by a pulsed, frequency tunable, narrow linewidth laser emitting in the ultraviolet. At the wavelength 269.5 nm, a concentration of 10 % of sulfur hexafluoride has been detected and the spectral signature shows some overlap with a carbon dioxide resonant spectral line. At 322.45 nm, we achieve better spectral definition. Based on successes using a similar approach for trace nitric oxide detection, we expect to be able to extend this approach to the detection of trace levels of SF₆ in the atmosphere for greenhouse gas monitoring.