High-field ESR and proton NMR in TDAE-C-70

High-field ESR spectra of powdered TDAE-C-70 at 245 GHz as well as methyl-proton-NMR spectra have been measured between room temperature and 4 K. Whereas the position of the main high-field ESR line of TDAE-C-70 is, in contrast to TDAE-C-60, independent of temperature, an additional ESR line appears at the low-field side below 50 K that shifts to lower fields with decreasing temperature. This seems to show the presence of field-induced shea-range magnetically ordered clusters in TDAE-C-70 at low temperatures, In contrast to TDAE-C-60, only one proton-NMR line that does not shift with decreasing temperature is seen in TDAE-C-70. This indicates the absence of superexchange between the C-70(-) ions across the TDAE methyl groups thus perhaps explaining the absence of a long-range magnetic ordering transition in this system. [S0163-1829(97)01842-0].