LASER SPECTROSCOPY OF U-I USING STEPWISE EXCITATION AND FLUORESCENCE DETECTION

We report 138 Ui odd levels in the region 32260-34900 cm** minus **1 and 16 even levels in the region 49500-49900 cm** minus **1. These levels are reached by two- or three-step selective dye laser excitation, respectively, and detected by fluorescence to lower levels. J values are assigned by identifying decays to known lower levels. Unique J values are presented for 64 levels and partial assignment (two possibilities) for 42 levels. A transition array is given indicating 427 fluorescence lines observed in the blue-green region. The exponential time decay of the fluorescence intensity provides direct determination of excited state lifetimes. Radiative lifetimes of 135 levels are presented.