Redox states of C/sub 60/ and C/sub 70/ measured by EPR and optical absorption spectroscopy

Summary form only given. We have measured EPR and visible-NIR spectra during reduction and oxidation of C/sub 60/ and C/sub 70/. The reduction was carried out on potassium in THF solution under high vacuum, while oxidation was performed with SbCI/sub 5/ in CH/sub 2/CI/sub 2/. Characteristic long wavelength absorption bands and their isosbestic points for the mixed equilibria of charged states could be used for the assignment of individual redox states up to the hexaanion. These optical transitions reflect the energy seperation of the T/sub 1u/ and T/sub 1g/ orbitals in C/sub 60/ which loose their threefold degeneracy upon charging. Careful analysis also enabled clean identification of paramagnetic species by linewidth and g-values. High resolution ENDOR is applied in the search for the /sup 13/C-couplings in natural abundance.