PhD student seminar by Emelie Olsson: Multi-particle coincidence studies of disulfur

Abstract

Using time-of-flight electron and ion coincidence techniques, the ionisation spectra and decay dynamics of doubly (and more highly charged) atomic and molecular species can be revealed. The double ionisation spectrum of the reactive intermediate disulfur molecular species (S2) is still unknown in the literature, but it is of great interest for at least two reasons: 1) as the analogue to the known spectra of molecular oxygen, and 2) as an important constituent of the atmosphere of Jupiter and its moons. We have succeeded in obtaining the first ever double ionisation spectra of S2, both by using VUV photons provided by a helium discharge lamp in Gothenburg and by using soft X-rays provided by the synchrotron radiation storage ring BESSY-II. The S2 sample was produced by heating mercury sulfide (HgS), which vapor at a suitably chosen temperature consists of two main constituents: S2 and atomic Hg. Because the spectra of the latter are known, an advanced multi-coincidence analysis is particularly useful for retrieving S2 spectra.