Coherent saturation effects in laser induced fluorescence detection of reaction products

Laser induced fluorescence detection of reaction products is now a wide-spread technique. When the laser coherence time is longer than the time spent by a molecule in the laser beam, the saturation effects of the laser-molecule interaction cannot be described by rate equations. In this paper we present a simple theoretical description of these effects and detailed experimental verifications. These results are quite important if one wants to derive reliable population measurements from the laser induced fluorescence signals in the case of coherent saturation.