title: The interaction of He(-) with fullerenes.
abstract: The effects of interactions between He(-) and clusters of fullerenes in helium nanodroplets are described. Electron transfer from He(-) to (C60)n and (C70)n clusters results in the formation of the corresponding fullerene cluster dianions. This unusual double electron transfer appears to be concerted and is most likely guided by electron correlation between the two very weakly bound outer electrons in He(-). We suggest a mechanism which involves long range electron transfer followed by the conversion of He(+)into He2 (+), where formation of the He-He bond in He2 (+) releases sufficient kinetic energy for the cation and the dianion to escape their Coulombic attraction. By analogy with the corresponding dications, the observation of a threshold size of n ≥ 5 for formation of both (C60)n (2-) and (C70)n (2-) is attributed to Coulomb explosion rather than an energetic constraint. We also find that smaller dianions can be observed if water is added as a co-dopant. Other aspects of He(-) chemistry that are explored include its role in the formation of multiply charged fullerene cluster cations and the sensitivity of cluster dianion formation on the incident electron energy.
authors.affiliation: Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria.
authors.forename: Andreas
authors.initials: A
authors.lastname: Mauracher
authors.affiliation: Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria.
authors.forename: Matthias
authors.initials: M
authors.lastname: Daxner
authors.affiliation: Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria.
authors.forename: Stefan E
authors.initials: SE
authors.lastname: Huber
authors.affiliation: Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria.
authors.forename: Johannes
authors.initials: J
authors.lastname: Postler
authors.affiliation: Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Renzler
authors.affiliation: Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria.
authors.forename: Stephan
authors.initials: S
authors.lastname: Denifl
authors.affiliation: Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria.
authors.forename: Paul
authors.initials: P
authors.lastname: Scheier
authors.affiliation: Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Ellis