Raman and infrared studies of single-crystal C60and derivatives

The authors describe results of Raman and infrared studies of single crystals of pure C 60 , CS 2 solvated C 60 (C 60 .1.5CS 2 ) and of (BEDT-TTF) 2 C 60 (BEDT-TTF is bisethylenedithio tetrathiafulvalene of ET). They have observed phonon shifts in the crystal surfaces using Raman scattering which they assign to diffusion of molecular oxygen into the crystals; the results indicate that the presence of molecular oxygen hinders rotation of C 60 molecules in the crystals. The four T 1u vibrational modes in the infrared spectrum of pure C 60 show fine structure which they attribute to Fermi resonances. They show that C 60 vibrations in C 60 .1.5CS 2 crystals are less anharmonic than in pure C 60 crystals.