MICROSCOPIC STRUCTURE OF COLLECTIVE DENSITY OSCILLATIONS C-60 AND C-70

The microscopic structure of the photo-excited plasmon excitation in C -60 and C-70 is investigated using linear response theory. One finds t hat 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 equ ilibrium symmetry (D-5h) of this fullerene. Furthermore, it is found t hat the coupling of the plasmon to the normal modes of vibration of th e fullerenes provides a sizeable contribution to the lineshape, withou t significantly affecting the linewidth. This coupling is found to be active already at T = 0, exhibiting a weak temperature dependence.