Charging up the cold: Formation of doubly- and triply-charged fullerene dimers in superfluid helium nanodroplets

TL;DR

This study demonstrates the formation and stabilization of doubly- and triply-charged fullerene dimers within superfluid helium nanodroplets, revealing their resilience against Coulomb explosion due to efficient cooling and ionization processes.

Contribution

It provides experimental evidence and theoretical support for the stability of doubly- and triply-charged fullerene dimers, a novel finding in fullerene chemistry within helium nanodroplets.

Findings

Detection of (C60)2^{2+} and (C60)2^{3+} ions.

Identification of dimers as the smallest stable charged fullerene clusters.

Low Coulomb barrier (<0.4 eV) prevents dissociation of these complexes.

Abstract

Sequential ionization of fullerene cluster ions (C$_{60}$)$_{n}^{+}$ within multiply-charged helium nanodroplets leads to the intriguing phenomenon of forming and stabilizing doubly- and triply-charged fullerene oligomers. Surprisingly, we have detected (C$_{60}$)$_{2}^{2+}$ and (C$_{60}$)$_{2}^{3+}$, indicating that dimers, rather than the previously established pentamers and dodecamers, are the smallest fullerene cluster sizes capable of stabilizing two and even three charges. This remarkable resilience against Coulomb explosion is achieved through efficient cooling within the superfluid environment of helium nanodroplets, and a sequential ionization scheme that populates covalently bound or physisorbed fullerene dimers. Calculations support the stability of four differently bonded (C$_{60}$)$_{2}^{2+}$ and (C$_{60}$)$_{2}^{3+}$ isomers and predict a low Coulomb barrier (<0.4 eV) preventing even dissociation of cold van der Waals complexes.