THE (2-COOLED BR-2(1) REMPI SPECTROSCOPY OF JET)

The (2 + 1) REMPI spectrum of Br-2 in the 56 000-85 000 cm(-1) region is re-examined using jet cooling and mass resolved ion detection. Apar t from the lowest three gerade Rydberg states, which on energetic grou nds must be members of the 5s cluster, all higher states are reassigne d to two Omega components of the nd-series, with n ranging from 4 to 1 2. Omega values are deduced from rotational contour analysis and inten sity ratios under linear and circular polarization. The simplicity of the observed spectra in the midst of a dense manifold of Rydberg state s is discussed in terms of the Omega(c)(lambda m(s))(Ry) coupling a sc heme and it is proposed that only those states with a large singlet co mponent are seen. The effect of different virtual paths in accessing t he a and d-series is evident in the rotational line contours of the 0 <-- 0 = Omega transitions. Previous work on Cl-2 and I-2 is also consi dered briefly and similar reassignments are suggested. (C) 1998 Publis hed by Elsevier Science B.V.