DOPPLER-LIMITED LASER-INDUCED FLUORESCENCE STUDIES OF $Cl_{2}$, $Br_{2}$, BrF, AND IF

Abstract

Rotationally-resolved Laser excitation spectra of the $B^{3} \Pi(o_{(u)}^{+})-X^{1} \Sigma^{+}_{(g)}$ transitions of $Cl_{2}, Br_{2}, BrC1, BrF$ and IF are reported. Pre-dissociation energies and radiative lifetimes for the excited B states will be presented. $C1_{2}(B)$ ia strongly predissociated above $v^{\prime} = 12$ and lifetimes of all higher vibrational levels are $\leq 50$ ns. However, the radiative lifetime of $C1_{2}(B, 10 \geq v^{\prime} \geq 7)$ is $80\,\mu s. Br_{2}(B)$ shows predissociation of a different type throughout the vibrational levels $24 \geq v^{\prime} \geq 11$ The rate coefficient for predissociation $\Gamma_{P}$ varies strongly with both $v^{\prime\prime}$ and j^{\prime}: \[ \Gamma_{p} = k_{v^{\prime}}{J^{\prime}}(J^{\prime} + 1) \] The radiative lifetime of $Br_{2}$(B) has been determined for several v^{\prime} levels. Collision-free lifetimes of BrCl(B), BrF(B) and IF(B) are reported. Predissociation yields new values for the ground-state dissociation energies of BrF and IF. The influence of R-T and V-V collisions on observed fluorescence lifetimes of levels near predissociation is extremely great. Collision dynamics within the excited B states of the interhalogens are discussed.