Direct Observation of Electron Spin Density on TDAE Cations in the Ferromagnetic State of Solid TDAE-C60

K. I. Pokhodnia and V. Barchuk Institute of Semiconductors, Ukrainian Academy of Sciences, Nauki Avenue 45, Kiev 252650, Ukraine (Received 15 January 1999; revised manuscript received 7 April 1999) 14N electron spin echo envelope modulation (ESEEM) and 1H nuclear magnetic resonance (NMR) techniques have been employed in order to measure the unpaired electron spin density of amino nitrogens and CH3 protons, in the low temperature ferromagnetic state of solid TDAE-C60. Well resolved 14N ESEEM patterns were obtained for the first time below 9 K, and their analysis reveals an extremely low unpaired electron spin density on specific TDAE nitrogen sites. Also, 1H NMR line shape measurements corroborate a stepwise increase of the electron spin density on the CH3 protons below 9 K that is accompanied by the onset of an activated law for 1H 1 T1 with temperature.