SPIN-ORBIT-COUPLING IN H3

The fine-structure splittings of the 3d 2E" and 2A1' states of H-3 are measured using fast neutral-beam laser spectroscopy. The splittings are analyzed in terms of the rotational mixing of the E" and A1' states to yield a value for the spin-orbit coupling constant of H-3 very close to those of the H and Li atoms. Contrary to previously published values of 40-90-mu-s, but in agreement with a recent measurement by Helm and co-workers, we find a lifetime of less than 2.1-mu-s for the long-lived 2p 2A2" N = K = 0 state. The spin-orbit contribution to predissociation of this state is discussed.