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Abstract: Primary steps in the interaction of high energy photons with water creating multiply ionised products are examined experimentally and theoretically. Double Auger decay from a 1s-hole state populates triply ionised states between 80 and 140eV binding energy. Ejection of one 1s electron and one valence electron gives states around 570eV which decay to triply ionised states between 75 and 110eV. Nuclear motion in these states competes with Auger decay and substantially modifies the final state spectra. The double core–hole state from ionisation of both 1s electrons is found at 1171±1eV and calculated at 1170.85eV. [Copyright &y& Elsevier]

Abstract: Triple ionisation of methane by decay of the singly charged ion with a 1s vacancy produces a trication spectrum starting near 70eV binding energy. Vibrational excitation in the initial hole state broadens and shifts the triple ionisation bands. Ionisation through core-valence doubly ionised states gives lower triple ionisation onsets and changes the spectral intensity pattern in accordance with retention of the initial valence holes in course of the double Auger effect. The double Auger effects occur both directly and as cascades, the different pathways producing different electron distributions and final state spectra. [Copyright &y& Elsevier]

Resonant and normal Auger electron spectra associated with an O1s initial vacancy of the O2 molecule have been recorded using photon energies of 541.80, 541.97 and 650 eV. The resonant Auger spectra obtained at 541.80 and 541.97 eV are interpreted as composed essentially of two characteristic parts, one between 10 and 35 eV binding energy reminiscent to direct photoionisation, and another, above 35 eV, associated primarily with spectator decay of the intermediate core-hole state. The spectra above 35 eV owe some similarity to the ordinary Auger electron spectrum recorded at 650 eV, and an interpretation is made in terms of Rydberg series in the cation converging towards the dicationic ionisation limits. The interpretation is based on a relaxation model introduced earlier for atomic resonant Auger spectra. The assignments of the resonant spectra assume that the relevant intermediate neutral states at 541.80 and 541.97 eV governing the Auger decay are essentially the ν=0 and 1 vibrational components of the (O1s)−1 4pσ Rydberg state. Arguments for this interpretation are given. [Copyright &y& Elsevier]