SPIN-SPIN INTERACTION IN THE T-3(2G) EXCITED-STATE OF C-60

The zero-field splitting found in spin resonance in the excited T-3(2g ) state of neutral C-60 has a lower symmetry than is predicted by the usual Jahn-Teller (JT) coupling theory. The effect of spin-spin coupli ng in the JT split state is discussed, and it is shown that the observ ed value of \E/D\, the ratio of the spin Hamiltonian constants, gives information about the nature of the distortion. It is proposed that th e ground-state distortion departs slightly from D-5d symmetry because of the presence of an unexpected, but small, high-order term in the en ergy.