Ab initio calculations for the concerted elimination of 1, 2‐bromochloroethane monocation (1,2‐C₂H₄BrCl⁺) to C₂H₄⁺ and BrCl are performed using the Minnesota density functional M06‐2X and the def2‐TZVP basis set. Ab initio calculations are also carried out for the concerted elimination of 1,2‐C₂H₄BrCl⁺ to C₂H₄ and BrCl⁺ because the positive charge can be assigned to either moiety in the dissociative ionization process of 1,2‐C₂H₄BrCl⁺. Our results demonstrate that the concerted elimination channel of 1,2‐C₂H₄BrCl⁺ to C₂H₄⁺ and BrCl is preferred and that 1,2‐C₂H₄BrCl⁺ surpasses two energy barriers and then separates into C₂H₄⁺ + BrCl through an asynchronous concerted process. Experimentally, we confirm that this elimination channel is from the dissociative ionization process of 1,2‐C₂H₄BrCl⁺ by using dc‐slice imaging technique. The time‐of‐flight mass spectra of 1,2‐bromochloroethane induced by femtosecond laser pulses show that C₂H₄⁺ occurs at a laser intensity of 6.0 × 10¹³ W/cm², and BrCl⁺ occurs at a higher laser intensity than C₂H₄⁺. This finding is consistent with the theoretical result that the appearance energy of C₂H₄⁺ is lower than that of BrCl⁺. As such, the low‐velocity component of BrCl⁺ is absent from our sliced images.

中文翻译：

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协同消除1,2-溴氯乙烷单阳离子成C2H4 +和BrCl的理论和实验研究

使用明尼苏达州密度函数M06-2X和def2-TZVP基础进行从头算计算，以协同消除1,2-溴氯乙烷单阳离子（1,2-C ₂ H ₄ BrCl ⁺）为C ₂ H ₄ ⁺和BrCl组。还进行了从头算计算以协调消除1,2-C ₂ H ₄ BrCl ⁺到C ₂ H ₄和BrCl ^+，因为在1,2-的解离电离过程中可以将正电荷分配给任一部分C ₂ H ₄ BrCl ⁺。我们的结果表明，首选的1,2-C ₂ H ₄ BrCl ⁺协同消除通道为C ₂ H ₄ ⁺和BrCl，并且1,2-C ₂ H ₄ BrCl ⁺超过两个能垒，然后分离为C ₂ H ₄ ⁺ + BrCl通过异步协同过程进行。通过实验，我们确认该消除通道来自1,2-C ₂ H ₄ BrCl ⁺的解离电离过程通过使用直流切片成像技术。飞秒激光脉冲诱导的1,2-溴氯乙烷的飞行时间质谱表明，C ₂ H ₄ ⁺发生在6.0×10 ¹³  W / cm ²的激光强度下，而BrCl ⁺发生在较高的激光强度下比C ₂ H ₄ ⁺。这一发现与C ₂ H ₄ ⁺的表观能量低于BrCl ⁺的表观能量的理论结果一致。因此，切片图像中不存在BrCl ⁺的低速度成分。