Two-photon absorption laser-induced fluorescence spectroscopy (TALIF) can provide a direct measurement of absolute atomic densities with high temporal and spatial resolution. Of particular challenge is the calibration method, since knowledge of collision rates outnumbering optical transition rates under atmospheric pressure conditions is required. In order to investigate the fast collisional ‘quenching’ processes acting on the laser excited states and finally to overcome the limitation regarding the quantitative density measurement, a tunable UV Fourier-limited pico-second laser system is set up at QUB. The concept, as shown below, comprises various optical techniques ranging from second harmonic generation (SHG) and optical amplification (OA) in crystals, pulse stretching and compression up to coherent white light generation (WLG).
This activity is in collaboration with several CPP members: B. Dromey, F. Garcia, J. Greenwood, R. King, G. Nersisyan, I. Williams, M. Zepf.
Information on the TALIF diagnostic can be found in
Niemi K, Schulz-von der Gathen V and Döbele H F, Plasma Sources Sci. Technol. 14 375 (2005).