193 nm photolysis of CHCl<sub>3sub>: Probe of the CH product by CRDS

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• 作者：Claire Romanzin ; B&#xe9 ; renger Gans ; St&#xe9 ; phane Douin ; S&#xe9 ; verine Boy&#xe9 ; -P&#xe9 ; ronne ; Dolor&#xe8 ; s Gauyacq
• 关键词：Pulsed photolysis ; CHCl<sub>3sub> ; Chloroform ; Methylidyne radical ; Cavity ring-down absorption spectroscopy ; Trichloromethane ; CH radical
• 刊名：Chemical Physics
• 出版年：2008
• 期刊代码：18_03010104
• 类别：ch
• 出版时间：3 July 2008
• 卷：351
• 期：1-3
• 页码：77-82
• 文件大小：253 K

摘要

The CH radical production induced by 193 nm two-photon photolysis of CHCl<sub>3sub> has been measured for the first time via the cavity ring-down absorption spectroscopy of its A–X bands, using a commercial nanosecond pulsed dye laser. The range of pressure and laser intensity, as well as the time window detection, have been carefully chosen to ensure a constant CH number density during the measurement and to avoid post-photolysis reactivity. Internal energy distribution of the CH(X<sup>2sup>II) fragment has been derived from population distribution simulations, leading to an average vibrational temperature T<sub>vibsub> = 1900 ± 50 K and rotational temperature T<sub>rotsub> = 300 ± 20 K. Two competing mechanisms can be invoked for the CH production channel: either two-photon absorption via resonant excited states of CHCl<sub>3sub> leading to dissociation of excited CHCl<sub>3sub>, or two-photon sequential dissociation via the formation of the vibrationally excited CHCl<sub>2sub> fragment. The latter mechanism is proposed to be the prominent process for CH formation.