Tunneling within localized states in nitrosyl myoglobin

Abstract
The temperature (T) dependence of the spin lattice relaxation time of nitrosyl myoglobin (MbNO) was measured in the range from 9 to 310 K. Both powdered and solution samples exhibit an unexpected dependence. Experimental data is well fitted by a T n function with n=2.2±0.3 in this large temperature range. This result is interpreted within the tunnelinglocalized states model associated with the existence of conformational equilibrium in MbNO.