I2 molecular elimination in single-photon dissociation of CH2I2 at 248 nm by using cavity ring-down absorption spectroscopy
- Citation:
- Chen, S-Y, Tsai P-Y, Lin H-C, Wu C-C, Lin K-C, Sun BJ, Chang AHH. 2011. I2 molecular elimination in single-photon dissociation of CH2I2 at 248 nm by using cavity ring-down absorption spectroscopy. Journal of Chemical Physics. 134, Number 3
Abstract:
Following single-photon dissociation of CH2I2 at 248 nm, I2 molecular elimination is detected by using cavity ring-down absorption spectroscopy. The technique comprises two laser beams propagating in a perpendicular configuration, in which a tunable laser beam along the axis of the ring-down cell probes the I2 fragment in the B 3 ou + - X 1 g + transition. The nascent vibrational populations for v 0, 1, and 2 levels are obtained with a population ratio of 1:(0.65 0.10):(0.30 0.05), corresponding to a Boltzmann-like vibrational temperature of 544 73 K. The quantum yield of the ground state I2 elimination reaction is determined to be 0.0040 0.0025. With the aid of ab initio potential energy calculations, the pathway of molecular elimination is proposed on the energetic ground state CH2I2 via internal conversion, followed by asynchronous three-center dissociation. A positive temperature effect supports the proposed mechanism. © 2011 American Institute of Physics.
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