Nascent vibrational distributions of BaBr were studied for the reaction Ba+CF3Brthinsp;rarr;BaBr+CF3. In a crossed beam configuration of supersonic CF3Br beam and effusive Ba beam, the product state distribution was measured by the laser induced fluorescence as a function of collision energy. The vibrational distribution of BaBr clearly showed a bimodal feature. At low collision energy, BaBr was produced preferentially around ngr;Prime;=32, while at some higher collision energy, another vibrational component gained intensity at around ngr;Prime;=15. The average vibrational energy of the higher vibrational component was about 80percnt; of the total available energy, and that of the lower, about 35percnt;. The bimodality of vibrational distribution indicates that the reaction Ba+CF3Br proceeds along two reaction pathways. In one pathway, Ba approaches in the direction of Brndash;CF3, and forms BaBr in low vibrational states. Whereas in the other, the atom approaches in the CF3ndash;Br direction, and leads to a high vibrational excitation of BaBr. The branching ratio to the former pathway increases with collision energy.
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