Resonant-state energy, series-convergent

The series limit on which the autoionising resonances converge may or may not be stable. If the corresponding parent ion state can decay ra-diatively, then because radiative widths are (for low excitation energies) usually much smaller than autoionisation widths, the series observed is not much affected until high values of n. On the other hand, if the parent ion state itself lies above the double-ionisation threshold, it becomes susceptible to particle decay and acquires its own intrinsic width through autoionisation. 

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