HIGH-SENSITIVITY ELECTRON-PARAMAGNETIC-RESONANCE OF MN-12-ACETATE

The energy diagram of Mn-12-acetate is probed close to the top of the anisotropy barrier using a novel, high-sensitivity, electron paramagne tic resonance technique. Multiple resonances, and their temperature de pendence, are observed from 35 to 115 GHz, for a single high-quality c rystal. The data are sufficiently detailed to make extremely accurate comparisons with predictions based on a spin S = 10 Hamiltonian. Altho ugh overall agreement is good, we find evidence for possible inadequac ies of this model.