C68: A non-IPR fullerene capable of binding extraordinary amounts of Cs atoms

The non-IPR fulleride compound CsxC68 was investigated in analogy to previous experiments on CsxC58. While the vibrational properties as well as the electronic structure in the valence band range appear to be pretty similar to CsxC58, a striking difference could be observed by XPS and Photoemission Microscopy analysis: apparently, C-68 forms different phases within a thick film including islands in which it is able to store more than 70 Cs atoms per fullerene cage and to keep these amounts even after annealing over 1100 K. This means that CsxC68 constitutes the highest alkali metal doping degree of any Fullerene species known so far. Spatially resolved photoemission analysis also revealed that the Cs-rich fulleride phases constitute a unique chemical state that has never been observed before.