Ion Imaging of MgI+ Photofragment in Ultraviolet Photodissociation of Mass-Selected Mg+ICH3 Complex,The Journal of Physical Chemistry A

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Ion Imaging of MgI+ Photofragment in Ultraviolet Photodissociation of Mass-Selected Mg+ICH3 Complex
The Journal of Physical Chemistry A ( IF 2.7 ) Pub Date : 2018-05-22 00:00:00 , DOI: 10.1021/acs.jpca.8b01944
Kenichi Okutsu ₁ , Kenichiro Yamazaki ₁ , Motoyoshi Nakano _{1,

2} , Keijiro Ohshimo ₁ , Fuminori Misaizu ₁

Affiliation

We have observed images of MgI⁺ fragment ions produced in ultraviolet laser photodissociation of mass-selected Mg⁺ICH₃ ions at 266 nm. Split distribution almost perpendicular to the polarization direction of the photolysis laser was observed in the photofragment image. Potential energy curves of Mg⁺ICH₃ were obtained by theoretical calculations. Among these curves, the excited complex ion dissociated along almost repulsive potentials with several avoided crossings, which was connected to MgI⁺ + CH₃. In the ground state of Mg⁺ICH₃, the CH₃I was bonded with Mg from the iodine side, and the Mg–I–C bond angle was calculated to be 101.1°. The theoretical results also indicated that the dissociation occurred after the 5²A′ ← 1²A′ photoexcitation, where the transition dipole moment was almost parallel to the Mg–I bond axis. The MgI⁺ and CH₃ fragments dissociated each other parallel to the direction connecting those center-of-masses, which was 67° with respect to the transition dipole moment of 5²A′ ← 1²A′ photoexcitation. Therefore, the fragment recoil direction was assumed to approach perpendicular tendency against the polarization direction under the fast dissociation process. However, calculated potential energy curves showed a complicated reaction pathway for MgI⁺ production, including nonadiabatic processes, although the experimental results indicated the fast dissociation reaction.

中文翻译：

质量选择的Mg ⁺ ICH _3配合物在紫外光解离中的MgI ⁺光致碎裂离子成像

我们已经观察到在质量选择的Mg ⁺ ICH ₃离子的紫外激光光解中在266 nm处产生的MgI ⁺碎片离子的图像。在光碎片图像中观察到几乎垂直于光解激光器的偏振方向的分裂分布。通过理论计算获得了Mg ⁺ ICH _3的势能曲线。在这些曲线中，激发的复合离子沿着几乎排斥的电势解离，避免了几次交叉，并与MgI ⁺ + CH _3连接。在Mg ⁺ ICH ₃的基态下，CH ₃我从碘一侧与Mg结合，Mg–I–C的结合角经计算为101.1°。理论结果还表明，解离发生在5 ² A'←1 ² A'光激发之后，跃迁偶极矩几乎平行于Mg–I键轴。MgI ⁺和CH ₃碎片彼此平行，平行于连接这些质心的方向解离，相对于5 ² A'←1 ²的跃迁偶极矩为67°A'光激发。因此，在快速离解过程中，假定碎片的反冲方向接近极化方向的垂直趋势。然而，计算的势能曲线显示了MgI ⁺产生的复杂反应途径，包括非绝热过程，尽管实验结果表明该反应快速解离。

更新日期：2018-05-22

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