Double resonance time-resolved measurements

A successful technique for studying collision induced transitions in electronic ground states is based on time-resolved double resonance [13.78]. The method is explained by Fig. 13.17. A pulsed laser LI tuned to an infrared or optical transition i) -+ k) depletes the lower level l) = (vj",Jj"). The depleted level is refilled by collisional transitions from other levels. A second weak probe laser L2 is tuned to another transition i) —> m) starting from the depleted lower level i). If the pump- and probe-laser beams overlap within a path length Az in the absorbing sample, the absorption of the probe-laser radiation can be measured by monitoring the transmitted probe-laser intensity... 

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