Medium effects on the spectroscopy and intramolecular energy redistribution of C60 in cryogenic matrices

A review with 30 refs. on some of the authors works on the absorption, excitation and emission spectra of C60 embedded in rare gas matrixes while stressing the role of the environment. The gas phase resonant 2-photon ionization spectrum of C60 is reanalyzed in the light of previous work and the energy of the lowest 3 excited singlet states is detd. with precision. In matrixes, the visible absorption bands are red shifted by an amt. ranging from .apprx.30 cm-1 in Ne matrixes to .apprx.330 cm-1 in Xe matrixes. The obsd. reversal of state ordering of the lowest 2 singlets states (T1g and T2g) between Ne and Ar matrixes (in emission) and in Ne matrixes, between the absorption and emission spectra, is attributed to different Stokes shifts of the T1g and T2g states and to the small energy splitting (.apprx.50 cm-1) between them. Finally, a detailed picture of the intramol. energy redistribution processes is obtained thanks to a combination of picosecond fluorescence expts. and femtosecond pump-probe transient absorption expts. The intramol. relaxation processes among the pure electronic levels of the lowest 3 singlet states are strongly medium dependent. Medium effects are manifest even on the very short time scale of the internal conversion in the singlet vibronic manifold. [on SciFinder (R)]