Vibrational energy transfer in CH3I |
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Authors: | Y Langsam SM Lee AM Ronn |
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Institution: | The City University of New York, Brooklyn College, Department of Chemistry, Brooklyn, New York 11210, USA |
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Abstract: | Previous works have reported vibration—vibration and vibration—translation transfer rates in the methyl halides. Using the technique of laser induced infrared fluorescence we have studied energy transfer in the concluding member of this series, CH3I. Following excitation by resonant lines of a Q-switch CO2 laser, infrared fluorescence has been observed from the v2, v5 as well as the 2v5, v1, v4 vibrational energy levels of CH3I. All the observed states exhibit a single exponential decay rate of 23 ± 2 ms?1 torr?1. Measurements have also been made on deactivation of the various modes by rare gases. The risetime of the v2, v5 levels was found to be approximately 101 ± 20 ms?1 torr?1, while that of the 2v5, v1, v4 levels was approximately 225 ± 45 ms?1 torr?1. Fluorescence was not detected from the v3 level. These results are discussed in terms of SSH type theoretical calculations, and comparison is made with the results obtained for other members of the methyl halide series, namely CH3F, CH3Cl and CH3Br. |
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