We have stored positively charged fullerene ions C(+)(n) (n even, from 48 to 70 and 76), C(2+)(60) and C(2+)(70) in an electrostatic storage ring and have measured the rate of emission of neutral fragments as a function of time. In the time range of the measurements, 50 micros to a few milliseconds, the rate decreases strongly due to radiative cooling of the molecules. Using the cooling rate predicted from a dielectric model, we have extracted the dissociation energies for C(2) loss from the measurements. As expected, the energies are largest for the "magic" fullerenes, C(50), C(60), and C(70), and the value of 9.8+/-0.1 eV for C(2) loss from C(+)(60) is in reasonable agreement with theory and with other recent experiments.

Abstract. Thermionic emission from hot fullerene anions, C − N , has been measured in an electrostatic storage ring for even N values from 36 to 96. The decay is quenched by radiative cooling and hence the observations give information on the intensity of thermal radiation from fullerenes. The experiments are analysed by comparison with a simulation which includes the quantisation of photon energy and the statistics of emission. Experiments with heating of the molecules with a laser beam confirm the interpretation of the observations in terms of radiative cooling and give an independent estimate of the cooling rate for C − 60 . The measured cooling rates agree in general within a factor of two with the prediction from a classical dielectric model of a thermal radiation intensity of ∼ 300 eV/s for C60 at 1 400 K, scaling approximately with the 6th power of the temperature and with the number of atoms in the molecule. PACS

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Thermal emission of electrons from clusters is enhanced after the absorption of photons. We have used this process to measure the photoabsorption cross sections of hot C 60 anions in the visible and nearinfrared part of the spectrum, using the ion storage ring ASTRID (Aarhus STorage RIng, Denmark).PACS. 78.40.R Absorption spectra of fullerenes -42.62.F Laser spectroscopy -79.40 Thermionic emission