物理化学学报 >> 2006, Vol. 22 >> Issue (04): 481-485.doi: 10.3866/PKU.WHXB20060418

研究论文 上一篇    下一篇

乙烯基A2A″电子态的振转分析

周晓国;刘世林   

  1. 中国科技大学化学物理系, 合肥微尺度物质科学国家实验室(筹), 合肥 230026
  • 收稿日期:2005-09-30 修回日期:2005-12-07 发布日期:2006-04-10
  • 通讯作者: 周晓国 E-mail:xzhou@ustc.edu.cn

Ro-vibrational Analysis of the A2A″ Electronic State of the Vinyl Radical

ZHOU Xiao-Guo;LIU Shi-Lin   

  1. Hefei National Laboratory for Physical Sciences at Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, P. R. China
  • Received:2005-09-30 Revised:2005-12-07 Published:2006-04-10
  • Contact: ZHOU, Xiao-Guo E-mail:xzhou@ustc.edu.cn

摘要: 通过193 nm光解丁烯酮分子产生乙烯基自由基(•C2H3). 经射流冷却后, 以另一束可调谐激光光解•C2H3, 生成的氢原子碎片经共振增强多光子电离(REMPI)过程, 记录氢离子信号随光解波长变化, 得到21180~21320 cm-1范围内乙烯基 A2A″(µ′5,6,8=1)←X2A′(µ″=0)跃迁的振转光谱. 结合量化计算和光谱拟合, 对该段光谱进行了细致的振转分析, 确定了各振动谱带位置, 识别了其中主要的转动跃迁. 由光谱拟合得到各振动能级的预解离寿命, 讨论了其与振动模式及激发转动量子数的依赖关系, 证实了理论预测的乙烯基A2A″电子态的面内解离机制.

关键词: 乙烯基自由基, 共振增强多光子电离, 预解离

Abstract: Vinyl radical was generated by photolysing methyl vinyl ketone at 193 nm, then was photodissociated by another tunable laser in the 21180~21320 cm1 range. The dissociated H atom fragments were ionized and detected by resonance-enhanced multiphoton ionization (REMPI) processes. The ro-vibrational action spectra of the A2A″(µ′5,6,8=1)←X2A′(µ″=0) of vinyl radical were recorded by monitoring the H+ ion intensity with dissociation laser wavelength. The corresponding analyses were obtained with the aid of quantum chemical calculations and spectroscopic simulations, vibrational bands and main rotational transitions were definitely assigned. Additionally, the predissociative lifetime was derived from the simulated linewidth, and its dependence on the vibrational mode and rotational quantum number was discussed. The in-plane dissociation mechanism of the state predicted by theoretical studies was confirmed.

Key words: Vinyl radical, Resonance-enhanced multiphoton ionization (REMPI), Pre-dissociation