OPTICAL-ABSORPTION OF GAS-PHASE C-60 AND C-70

We have measured optical absorption spectra of gas phase C60 and C70 f rom 1.9 to 6.5 eV at various temperatures up to 1000 K. The optical de nsity spectra of C60 and C70 have only three and six peaks, respective ly, in the measured spectrum range and can be reconstructed successful ly with the same number of Lorentz oscillators. This simple spectrum s tructure suggests a simple view for the electronic state of a C60 mole cule. We have estimated sublimation heats Of C60 and C70 at 1.7 and 1. 3 eV, respectively, from changes of absorption intensities with temper ature.