Investigation of the 2p ionization threshold region of Ar clusters by observation of the fluorescence lifetime

Time-resolved soft X-ray and vacuum ultraviolet fluorescence resulting from the decay processes of 2p inner-shell excited Ar clusters has been observed. Fluorescence with 3-10 ns lifetime is observed, and assigned as being cluster-specific. This fluorescence can be attributed to arising from the decay of excited states of either neutral or singly ionized atoms produced via energy transfer or electron transfer processes including the interatomic Coulombic decay mechanism. The time-uncorrelated neutral yield spectra arise from large Ar clusters.