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 C 60 3 - 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 C 60 3 - fullerides is found to be higher than that of C 60 4 - fullerides, agreeing with the trend found in heavy alkali fullerides. We propose possible structures of the metallic phases.