Laser pulse intensity versus duration

If fluorescence is excited by a laser pulse of a duration shorter than the lifetime of the excited state of an adsorbate, the subsequent decay of the emission intensity can be measured by time-resolved techniques. Then the slope of the logarithm of intensity versus time gives the total decay rate, 1/r. The part related to nonradiative relaxation is determined by the energy transfer to the substrate. Thus such measurements allow one to study different de-excitation channels at a surface. 

Fig. 11. Calculated energy transmission Tj versus peak laser intensity Jo for several values of the laser pulse durations At, and the dye parameters Tq = 0,173, a = 1,84 -10-16cm2, and Tf = 9.1 psec. (From Ref. 44>)...

Fig. 12.8 Diagram of radiation intensity I (W/cm ) versus laser pulse duration Tp (s), with the various laser-pulse-condensed-medium interaction regimes being indicated very qualitatively. At high radiation intensities I and energy fluences

The final form for Acl) (f), as well as the output intensity distribution on the observation plane P, depends on the form of and the response time tf versus the laser pulse duration tp. If the response time tf is longer than tp, the self-limiting effect is... 

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