Microscopic structure of collective density oscillations C60 and C70

The microscopic structure of the photo-excited plasmon excitation in C60 and C70 is investigated using linear response theory. One finds that Landau damping provides the main contribution to the lineshape and the linewidth of the Mie-type plasmon being able, in the case of C70, to mask the deformation splitting effect associated with the low equilibrium symmetry (D5h) of this fullerene. Furthermore, it is found that the coupling of the plasmon to the normal modes of vibration of the fullerenes provides a sizeable contribution to the lineshape, without significantly affecting the linewidth. This coupling is found to be active already atT=0, exhibiting a weak temperature dependence.