首页> 外文期刊>Physical chemistry chemical physics: PCCP >Near-UV photodissociation dynamics of CH2I2
【24h】

Near-UV photodissociation dynamics of CH2I2

机译:CH2I2的近紫外光解离动力学

获取原文
获取原文并翻译 | 示例
获取外文期刊封面目录资料

摘要

The near-UV photodissociation dynamics of CH2I2 has been investigated using a combination of velocity-map (slice) ion imaging and ab initio calculations characterizing the excited states. Ground state I(P-2(3/2)) and spin-orbit excited I*(P-2(1/2)) atoms were probed using 2 + 1 resonance-enhanced multiphoton ionization (REMPI) or with single-photon VUV ionization. Two-color ion images were recorded at pump wavelengths of 355 nm, 266 nm and 248 nm, and one-color ion images at the REMPI wavelengths of similar to 304 nm and similar to 280 nm. Analysis of the ion images shows that, regardless of iodine spin-orbit state, similar to 20% of the available energy is partitioned into translation E-T at all excitation wavelengths indicating that the CH2I co-fragment is formed highly internally excited. The translational energy distributions comprise a slow, "statistical" component that peaks near zero and faster components that peak away from zero. The slow component makes an increasingly large contribution to the distribution as the excitation wavelength is decreased. The C-I bond dissociation energy of D-0 = 2.155 +/- 0.008 eV is obtained from the trend in the E-T release of the faster components with increasing excitation energy. The I and I* ion images are anisotropic, indicating prompt dissociation, and are characterized by beta parameters that become increasingly positive with increasing E-T. The decrease in beta at lower translational energies can be attributed to deviation from axial recoil. MRCI calculations including spin-orbit coupling have been performed to identify the overlapping features in the absorption spectrum and characterize one-dimensional cuts through the electronically excited potential energy surfaces. The excited states are of significantly mixed singlet and triplet character. At longer wavelengths, excitation directly accesses repulsive states primarily of B-1 symmetry, consistent with the observed , while shorter wavelengths accesses bound states, also of B-1 symmetry that are crossed by repulsive states.
机译:CH2I2的近紫外光解离动力学已使用速度图(切片)离子成像和表征激发态的从头算的组合进行了研究。使用2 + 1共振增强多光子电离(REMPI)或单光子探测基态I(P-2(3/2))和自旋轨道激发的I *(P-2(1/2))原子。 VUV电离。在355 nm,266 nm和248 nm的泵浦波长下记录了两色离子图像,在REMPI波长下与304 nm和280 nm相似的单色离子图像被记录下来。对离子图像的分析表明,无论碘自旋轨道的状态如何,在所有激发波长下,约20%的可用能量均被分配为平移E-T,这表明CH2I共片段是高度内部激发的。平移能量分布包括一个缓慢的“统计”分量,其峰值接近零,而更快的分量则其峰值远离零。随着激发波长的减小,慢速成分对分布的贡献越来越大。 D-0 = 2.155 +/- 0.008 eV的C-1键解离能是从更快的组分随着激发能的E-T释放的趋势中获得的。 I和I *离子图像是各向异性的,表明迅速解离,并且具有β参数,随着E-T的增加,β参数变得越来越正。 β在较低平移能下的减少可归因于与轴向反冲力的偏差。已经进行了包括自旋轨道耦合在内的MRCI计算,以识别吸收光谱中的重叠特征,并表征通过电子激发势能表面的一维切变。激发态具有显着混合的单重态和三重态特征。在更长的波长处,激发直接进入主要与观察到的β一致的B-1对称性的排斥状态,而较短的波长进入也与排斥状态相交的B-1对称性的结合状态。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱:kefu@zhangqiaokeyan.com

京公网安备:11010802029741号 ICP备案号:京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有
  • 客服微信

  • 服务号