Dynamic Relaxation and Decay

In order to describe the correlation of motion between the core hole and the screening electrons, we must construct wave packets representing individual electrons in the atomic shells by superposing one-electron orbitals. In a perturbation expansion, electrons and holes will then appear to jump between different one-electron levels, and these processes can be discussed in terms of fluctuation and decay. Since the system is described as jumping between different configurations, the fluctuation process corresponds to con- 

The correlation pattern depends on the angular momentum transfer K between the core hole and the screening charge. For K = 0 there is a correlation between the radial motion, monopole fluctuation, of the core hole and the screening charge (Fig. 13 g) while for K 1 there is an angular correlation. Fig. 13 h describes the case of dynamic dipolar fluctuation (K = 1) where the core hole no longer is spherically distributed and where the 

It is interesting to note that in the quadrupole relaxation process discussed in Section 3.4 (Fig. 12) the core hole can be regarded as fluctuating between the different degenerate orbital magnetic sublevels. In this way, the core hole can form a static quadrupole moment and induce a quadrupole screening charge distribution. 

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