PRECISION LIFETIME MEASUREMENTS IN H-2 - DISAGREEMENT WITH THEORY

We have measured the lifetimes of three rovibrational levels-g (3) Sig ma(g)(+)(upsilon = 1,N = 2), i(3) Pi(g)(-)(upsilon = 0,N = 1), and j(3 ) Delta(g)(-)(upsilon = 1,N = 3)-in the n = 3 complex of H-2 with a pr ecision of 2%. On the basis of the first two measurements, we suggest that a previously neglected decay channel should be included in theore tical treatments and may have played an important role in an earlier e xperiment. Our value for the lifetime of j(3) Delta(g)(-)(upsilon = 1, N = 3) agrees well with the earlier experiment; the best theoretical e stimate lies almost 50% higher.