Mass-resolved resonance enhanced ionization study of complicated excited electronic states of Rb-2 near 430 nm and their predissociation dynamics

Abstract

We have investigated the Rb-2 430 nm system by resonance enhanced two-photon ionization and photofragment yield spectroscopy. Four electronically excited states have been assigned, and their two-channel (fast and slow) predissociation has been observed. For the 3 (1)Pi, 3 (1)Sigma(+)(u), 3 (3)Pi(u)(0(u)(+)), and 3 (3)Pi(u),(1(u)) states, electronic term values (T-e) and vibrational constants (omega(e) and omega(e)x(e)) have been determined. For the predissociation dynamics, we have observed the fast predissociation threshold between the isotopically shifted 3 (1)Pi(u) v ' = 14 levels of Rb-85(2) and (RbRb)-Rb-85-Rb-87 where the 4 D-2(5/2) + 5 S-2(1/2) atomic fine-structure limit is located. The 1 (3)Delta(u) state corresponding to the 4 2D(5/2) + 5 S-2(1/2) atomic fine-structure limit has been assigned to the predissociating perturber responsible for the fast channel. Also, we have found that the fast channel branches out into two finer product channels due to long-range potential crossing.