Absolute single photoionization cross-section measurements for Se + ions were performed at the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory using the photo-ion merged-beams technique. Measurements were made at a photon energy resolution of 5.5 meV from 17.75 to 21.85 eV spanning the 4s24p3 4S3/2o ground-state ionization threshold and the 2P3/2o,2P1/2o,2D5/2o, and2D3/2o metastable state thresholds. Extensive analysis of the complex resonant structure in this region identified numerous Rydberg series of resonances and obtained the Se2+ 4s24p2 3P2 and 4s24p2 1S0 state energies. In addition, particular attention was given to removing significant effects in the measurements due to a small percentage of higher-order undulator radiation.
|Physical Review A - Atomic, Molecular, and Optical Physics
|Published - Jul 11 2011