Partial lightsum method

It has first been observed by Tale and Gailitis [51] that after a sudden temperature change the tunnelling luminescence increase is delayed due to an inertial diffusive motion of defects the relevant theory was developed quite recently [55] and discussed above. On the other hand, when the defects are again frozen, a partial lightsum method can be used demonstrating clearly [95] that the concentration of close dissimilar defects has been enriched due to their preceding diffusive approach. 

Fig. 4.18. The tunnelling luminescence kinetics for F, Vk pairs in KBr (upper curves 1, 2, 3) vs. temperature stimulation (lower curves 1, 2, 3 respectively), a is the slope change after the stimulation is switched off. According to the partial lightsum method [37, 87-90] the insert (curve 4) yields the relative dissimilar defect distribution occurring after the temperature stimulation. Arrows show the change of both the tunnelling luminescence decay intensity I(t) and the spatial defect distribution caused by the stimulation a close defect concentration increases whereas that for the distant pairs decreases.

As it was shown above, the static kinetics of tunnelling luminescence is much simpler than the diffusion-controlled kinetics. The static tunnelling luminescence intensity often obeys the empirical Becquerel s law [87] I t) oc t ° , where the distinctive decay parameter a = —d ogI i)/ d ogt) is defined by the spatial distribution of defects only, usually considered to be either the isolated pairs of spatially well-correlated dissimilar defects (low dose irradiation) or the random mixture of dissimilar defects (high doses and/or high temperatures) [88]. Moreover, in the case of pairwise distribution, the partial lightsum method has been presented [88-91] in order to restorate the defect initial spatial distribution /(r) within geminate pairs -see equation (4.2.1) and below. What we have discussed here are the tran-... 

In the method of partial lightsums the lightsums S(t) of the tunnelling luminescence emitted during logarithmically increasing time intervals are measured instead of the ordinary luminescence intensity I(t) which allows us to estimate with the help of equations (4.2.3) and (4.2.6) the initial defect distributions... 

Therefore, the method of partial lightsums illustrates once more effects of the defect diffusion a number of close pairs increases, whereas that of distant pairs decreases, unlike the case of defect rotation. 

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