Microscopic structure of collective density oscillations C60 and C70

The microscopic structure of the photo-excited plasmon excitation in C-60 and C-70 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 C-70, to mask the deformation splitting effect associated with the low equilibrium symmetry (D-5h) 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 at T = 0, exhibiting a weak temperature dependence.