Spectator autoionization

PA = participant autoionization SA = spectator autoionization PDA = participant double autoionization, SDA = spectator double autoionization CA = cascade autoionization AD = Auger decay ASU = Augur decay with shake-up DAD = double Auger decay, ICD = interchannel decay. 

Several decay channels are possible. The most important are listed in Table II and are labeled PA (participant autoionization), SA (spectator autoionization), PDA (participant double autoionization), SDA (spectator double autoionization), and CA (cascade autoionization). 

Also called resonance Auger or autoionization spectator transition the spectator electron may also change its orbital, nt -> n t, mostly with t = t (shake-modified spectator transitions) see Section 5.1.2.1. 

If the autoionization process only depends on L rather than on / the excited atom has to be characterized by the L-dependent tensor components PkqiL) in place of the /-dependent ones. This makes sense anyway, since the excitation processes in heavy particle collisions are mostly spin independent. Therefore the spin can be regarded as spectator during the excitation process, and at time t = 0, when the excitation takes place, the density matrix factorizes into an L-dependent part and a spin-dependent one which is diagonal. The pkq L,T = 0) therefore characterize the excitation process and are the quantities that one would like to know in order to obtain information about excitation mechanisms. 

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