FLUORESCENCE OF AR(2P)-EXCITED ARGON CLUSTERS

Fluorescence of argon and argon clusters is investigated in the Ar(2p) -excitation regime (240-310 eV). Fluorescence excitation spectroscopy shows a different evolution as a function of the average neutral clust er size compared with total electron and ion yields as well as partial ion yields of mass-selected cluster ions. These differences are ratio nalized in terms of various multiple ionization processes occurring in argon clusters. The dispersed fluorescence shows a broad continuum be tween 165-290 nm which is interpreted as emission of the ''third conti nuum'' of argon. The results suggest that the process leading to fluor escence of clusters in the Ar(2p) regime is due to the radiative decay of doubly charged clusters.