Soft-x-ray-induced ionization and fragmentation dynamics of Sc3N@C80 investigated using an ion-ion-coincidence momentum-imaging technique

Abstract

The fragmentation dynamics of an endohedral fullerene, $\mathrm{S}{\mathrm{c}}_{3}\mathrm{N}@{\mathrm{C}}_{80}$, after absorption of a soft-x-ray photon, has been studied with an ion-ion-coincidence momentum-imaging technique. Molecular inner-shell ionization at 406.5 eV, targeting the Sc ($2p$) shell of the encapsulated $\mathrm{S}{\mathrm{c}}_{3}\mathrm{N}$ moiety and the C ($1s$) shell of the ${\mathrm{C}}_{80}$ cage, leads to the cage fragmentation through evaporation of ${\mathrm{C}}_{2}$, emission of small molecular carbon ions (${\mathrm{C}}_{n}{}^{+}$, $n\ensuremath{\le}24$), and release of Sc and Sc-containing ions associated with the carbon cage opening or fragmentation. The predominant charge states of Sc and Sc-containing ionic fragments are $+1$ despite an effective Sc valence of 2.4, indicating that charge transfer or redistribution plays an important role in the fragmentation of the encaged $\mathrm{S}{\mathrm{c}}_{3}\mathrm{N}$. Sequential emission of two out of the three Sc atoms of the encaged moiety, via Coulomb explosion in the form of $\mathrm{S}{\mathrm{c}}^{+}$ or Sc-containing ions, is significant. We also find that the resonant excitation of the Sc ($2p$) shell electrons significantly increased the yield of the parent $\mathrm{S}{\mathrm{c}}_{3}\mathrm{N}@{\mathrm{C}}_{80}$ and its fragment ions, partially attributed to the collision of the energetic Auger electrons from the Sc site with the carbon cage.