An experimental and theoretical characterization of the electronic structure of doubly ionised disulfur

Using time-of-flight multiple electron and ion coincidence techniques in combination with a helium gas discharge lamp and synchrotron radiation, the double ionisation spectrum of disulfur (S-2) and the subsequent fragmentation dynamics of its dication are investigated. The S-2 sample was produced by heating mercury sulfide (HgS), whose vapour at a suitably chosen temperature consists primarily of two constituents: S-2 and atomic Hg. A multi-particle-coincidence technique is thus particularly useful for retrieving spectra of S-2 from ionisation of the mixed vapour. The results obtained are compared with detailed calculations of the electronic structure and potential energy curves of S-2(2+) which are also presented. These computations are carried out using configuration interaction methodology. The experimental results are interpreted with and strongly supported by the computational results.