Radiative Cooling ofC60

We have studied the radiative cooling of negatively charged fullerene ions by following the thermionic emission as a function of time after injection into the heavy-ion storage ring ASTRID. It is argued that electron emission can be used as a calibrated thermometer to measure the cooling rate. For $C_{60}^{-}$ at $\sim 1500\mathrm{K}$ the cooling corresponds to a radiation intensity of $\sim 190\mathrm{eV}/\mathrm{s}$, which is 2 orders of magnitude more than expected from infrared active vibrations.