Sensing of Halocarbons Using Femtosecond Laser-Induced Fluorescence

A femtosecond laser-induced clean fluorescence technique was explored as a means to monitor halogenated alkanes in the atmosphere. Characteristic difluorocarbene radical (CF2) fluorescence in the UV-vis can be generated inside a femtosecond laser-induced filament for different halocarbons. We show that, due to different dissociation and excitation kinetics leading to fluorescence emission, it is possible to temporally resolve the characteristic fluorescence of CF2-containing halocarbons from that of background species, therefore enhancing the signal-to-noise ratio. Laboratory-scale experiments demonstrate the potential use of femtosecond laser-induced clean fluorescence for the remote sensing of halocarbons in the atmosphere. The combination of this detection strategy with LIDAR could allow the long-range monitoring of several atmospheric species with a single laser source, eventually leading to a better understanding of chemical and dynamic processes affecting global warming, ozone loss, tropospheric pollution, and weather prediction.