ChemAtom Seminar: M. Gatchell SU/Uni Innsbruck - Action spectroscopy with He nanodroplets

Action spectroscopy with He nanodroplets
Action spectroscopy using He atoms as messengers has proven itself to be a powerful tool in obtaining the gas phase absorption spectra of complex molecular ions. This was demonstrated particularly well with the identification of C60+ as the carrier of several diffuse interstellar bands (DIBs) in 2015. 

In Innsbruck we have been studying C60+ and corannulene (C20H10+) ions produced in superfluid He nanodroplets. By ionizing neutral droplets doped with these molecules we obtain the fullerene and PAH ions decorated with anything from a single He atom to many tens of atoms. Using mass spectrometric and action spectroscopy techniques we are able to deduce the size-dependent influence of the He solvation on the decorated ions, such as the formation of solvation layers and spectral shifts. With this technique we have shown that the first 32 He atoms around a C60+ induce a redshift that increases linearly with the number of He atoms, in good agreement with the results by Campbell et al.

I will present a study of how line profiles of C60+ systematically vary as a function of the number of solvating He atoms. I will also present results from recent spectroscopic measurements on corannulene cations, which show much richer variation in the redshifts induced by surrounding He atoms compared to C60+, and discuss the implications this has on studies of molecules other than the highly symmetric fullerenes.