A photoelectron study of resonance structure in the argon correlation satellites

Doubly excited neutral states of argon have been investigated by observing their decay into the 3p and 3s main ionisation lines and into the satellite ionic states. These were measured using photoelectron spectroscopy and monochromatic synchrotron radiation in the range 31.0 to 42.3 eV. The 3p and 3s main line constant ionic state spectra show structure due to the decay of doubly excited states but in general these are much less prominent than in the spectra for the satellites which are dominated by resonances, particularly close to threshold. There is also a strong selectivity with marked differences in the resonance structure observed in the decay to different satellite states. Four Rydberg progressions have been observed each of which is split into two series.