Branching ratios of autoionization from Eu 476p1/26d [J] autoionizing states**Project supported by the National Natural Science Foundation of China (Grant No. 11174218).

Abstract

The autoionization branching ratios from Eu 4f76p1/26d [J] autoionizing states to its 4f76s+ (9So), 4f76s+ (7So), and 4f75d+ (9Do) final ionic states are investigated with the combination of the three-step laser excitation and the velocity-map imaging technique. These different autoionizing states are excited via 4f76s6d 8DJ [J = 5/2, 7/2, and 9/2] intermediate states, respectively. The experimental photoelectron images are obtained, from which energy distributions of ejected electrons are achieved with the mathematical transformation. Furthermore, the energy dependence of the branching ratio is investigated within the autoionization resonance, by which population inversion is observed as an important characteristic. The J-dependence is also studied systematically. The validity of the well-known isolated core excitation technique used for obtaining the autoionization spectrum is also studied.