Comment on “Nuclear spin relaxation and non-ergodic quasi-equilibria”

Spin relaxation is described for a system of three accidentally degenerate nuclear spins that can be individually monitored, e.g., via heteronuclear scalar coupling partners. The exact treatment based on Bloch–Wangsness–Redfield theory is shown to be consistent with the stochastic Liouville equation correcting and extending earlier findings (Brüschweiler, Chem. Phys. Lett. 270 (1997) 217). The transition to the Solomon regime is discussed when degeneracy is removed.