Laser-induced transformation of Li4C60 and Na4C60 polymers into metallic monomeric fulleride phases

We demonstrate that laser irradiation on the narrow-gap insulator Li4C60 and Na4C60 polymers results in metallic monomeric structures, having the same Raman features as metallic fcc K3C60 and Rb3C60, with orientationally disordered C603- anions stable at ambient conditions. The Raman Ag(2) mode indicates that a single phase was obtained. Additionally, a monomeric A4C60-type phase (A = K, Rb) is observed in Na4C60 after irradiation. The electron-phonon coupling constants derived from Raman modes of C603- fullerides is found to be higher than that of C604- fullerides, agreeing with the trend found in heavy alkali fullerides. We propose possible structures of the metallic phases.

Laser irradiation induces Li4C60 and Na4C60 polymers into metallic monomeric structures with orientationally disordered C603- anions stable at ambient conditions.70