Infrared amplified spontaneous emission from the 0 +g (3P0) and 0 +g (1D2) ion-pair states of molecular bromine

Abstract

We report the observation of amplified spontaneous emission for the first time from the 0⁺_g (³P₀) and 0⁺_g (¹D₂) ion-pair states of Br₂ by using an optical–optical double resonance technique through the B ³Π(0⁺_u) valence state as the intermediate state. The strong infrared emission propagating along the incident laser radiation is assigned to the parallel ASE transitions from the 0⁺_g ion-pair states down to the nearby 0⁺_u ion-pair states. The subsequent UV fluorescence from the 0⁺_u states to the high vibrational levels of the ground state is also observed. By the Franck–Condon simulation of the cascade UV fluorescence, we determine the vibrational distributions in the 0⁺_u states populated by ASE, which are consistent with the intensity distribution in the dispersed infrared ASE spectrum. The lifetimes of the relevant ion-pair states are evaluated by analyzing the temporal profiles of the UV fluorescence.