Knowledge Bank

Taking advantage of matrix isolation (i.e. high density of species, low density of states, hindered rotations), we have carried out a spectroscopic study of $C60$ in rare gas matrices as well as in pure $C60$ films at low temperature. Absorption (in the range of 420 to 750 nm), emission and excitation spectra for excitation in the range of 550 to 650 nm have been obtained. Orbitally forbidden singlet-singlet transitions are observed between 480 and 650 nm in accord with absorption spectra of $C60$ in solution but with a better resolution and different matrix shifts. This last effect can be explained in terms of the different polarizabilities of the matrix atoms. High resolution absorption spectra of $C60$ in Ne provide structures comparable to those of the gas phase. A triple peaked emission band (680; 720; 800 nm) is observed in Ne, Ar and Kr matrices but not in Xe matrices. While the excitation spectra of the first two peaks reproduce quite well the absorption spectra, the 800 nm emission can only be excited in the long wavelength region of the absorption spectra, suggesting that its origin is a different electronic state.