NEAR-THRESHOLD SINGLE PHOTON DOUBLE IONIZATION OF NEON, ARGON, KRYPTON AND XENON OBSERVED BY ELECTRON ELECTRON COINCIDENCE SPECTROSCOPY

A photoelectron spectrometer composed of two analysers of different types has been used in an electron-electron coincidence mode to study photo-double ionization phenomena in neon, argon, krypton and xenon. Relative partial cross sections of the lowest three double ion states measured close to threshold would indicate that the predicted state selectivity is roughly adhered to except in the case of neon. The near-threshold angular behaviour of the ejected photoelectrons did not indicate a trend dependent on the symmetry of the state of the double ion as would be expected from theory.