The optical response of Li-4(+) and Li-7(+) exhibits three large maxima at photon energies between 1.9 and 3.6 eV, on which a fine structures could be resolved that has a peak to peak distance of about 30-40 meV. A high level ab initio calculation of Li-4(+) shows that this feature is due to vibrational structure of the excited electronic state. It is pointed out that the lifetime of the excited states exhibits a dramatic shortening with increasing particle size.