Predissociation lifetimes of the B-state of I79Br

Abstract

The predissociation of the B (3Π0+) state of I79Br is studied by measuring its one photon absorption spectrum in a cold molecular beam by REMPI detection of the atomic photo fragments. In this work, we present the absolute frequencies as well as the line shapes of the transitions to the vibrational levels v' = 22 to v' = 34 of the B (3Π0+) state. These results provide the lacking information needed to fully interpret the outcome of the femtosecond experiments. They also provide important spectroscopic data required to acquire a more accurate theoretical description of the intersecting 3Π0+ surfaces. The predissociative lifetimes of the short lived levels (τ < 2 ps) have been determined from the observed linewidth. It is found that the linewidths, and thus the predissociative lifetime, oscillate as a function of the vibrational quantum number. All observed spectral transitions obey a Fano-profile lineshape from which the Fano-parameters have been extracted.