INTRINSICALLY UNPOLARIZED FLUORESCENCE OF C-60

The fluorescence spectrum and the fluorescence steady-state anisotropy of C-60 in a toluene-ethanol 10 : 1 (v/v) mixture have been obtained at room temperature and at 140 K. At 140 K, where molecular rotation i s negligible during the excited-state lifetime, essentially zero fluor escence anisotropy was measured, irrespective of the excitation wavele ngth. It is concluded, in accordance with theoretical expectations, th at the fluorescence of C-60 is intrinsically unpolarized. C-60 is the first organic molecule to show this behaviour.