Photodissociation Dynamics of Gas-Phase BrICl- and IBr2 Anions
نویسندگان
چکیده
This work is the first study of mixed trihalide anions in the gas phase. We report the photochemistry and photodissociation dynamics of BrICland IBr2 anions near 400 nm. For BrICl-, two major photodissociation channels yielding IBrand IClproducts are observed. The photodissociation of IBr2 yields primarily IBranion products. No BrCland Br2 fragments are formed from BrICland IBr2, respectively, and the parent anions are ascribed linear [Br-I-Cl]and [Br-I-Br]structures, in agreement with ab initio calculations. The IBrand IClproducts are produced in highly vibrationally excited states. We observe fragment vibrational coherence in femtosecond pump-probe measurements by probing nascent IBrvia its photodissociation to I+ Br. The IBrvibrational periods observed in the photodissociation of BrIClcorrespond to excitations of ∼80% of the IBrdissociation energy (Do). In IBr2 dissociation, the average vibrational excitation of IBris 84-91% of Do. The high degrees of vibrational excitation raise questions about the effect of the proximity to the dissociation threshold on the dynamics of coherent wave packets. We analyze these dynamics analytically and by means of wave packet simulations and observe smearing of expected wave packet revivals.
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