High-pressure stability of Cs6 C60

The Cs6 C60 molecular crystal has been studied by Raman spectroscopy measurements and ab initio calculations under high pressure. The Raman scattering data have been collected from ambient pressure up to 45.5 GPa at room temperature. It is shown that the intercalation of cesium atoms in the C60 crystalline structure allows us to preserve the C60 molecules up to the maximum studied pressure, i.e., more than twice the amorphization pressure of the solid C60 fullerene crystal. The calculated pressure evolution of all the observed Raman mode frequencies is in good agreement with that obtained experimentally. In this work, the high-resolution measurements allow us to observe six Raman modes and several partners in doublets in addition to the Raman lines previously observed for the same system. The symmetry of all the observed modes has been identified through our calculations.