Relaxation kinetics of polarization moments

In particular, in the case of linearly polarized excitation through bPo bPo- and according to (3.19), three ground state polarization moments may emerge with k = 0,2 and 4. Indeed, substituting coefficients from Table 2.1 and Clebsch-Gordan coefficients from Table C.l into (3.19) we obtain 

If we insert (3.34) and (3.35) into (3.36) and then the result into (2.29) and (2.30) we obtain three exponentials in time dependence of the observable signals. However, in many cases, and in analogy with the data for excited states (Section 2.5), one ought not to expect considerable differences between 70, 72 and 74, which, as a rule, justify the monoexponential approximation (3.33). 

However, the alignment relaxation constant 72 may be measured separately by means of the method of laser-interrogated dichroism, as discussed in the preceding Section (Section 3.5]. Let us assume that in the scheme shown in Fig. 3.17 the strong field Eg is interrupted at time o  

It is simple to arrange the registration of the transient process in the case of fluorescent population considered in Section 3.4. For this purpose it is, for instance, sufficient that the first beam, which causes a transition J — J (Fig. 3.14) should act in short pulses Tp = GS(t). Then in the time dependence of the fluorescence produced by the continuous probe beam (cycle J — J[ — J f dotted line in Fig. 3.14) we observe the relaxation of the polarization moments of level J directly. 

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