非对称超短强激光场中乙腈二价阳离子内的定向氢迁移
Directional Hydrogen Migration in Acetonitrile Dication in Asymmetric Ultrashort Intense Laser Fields
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中文总结 AI 辅助
研究人员借助三维符合离子动量成像，发现双色非对称激光场可调控乙腈二价阳离子的定向氢迁移，隧穿电离使甲基指向小振幅侧，氢迁移后碎片不对称性降低且存在氘代效应。
中文摘要 AI 辅助
我们利用三维符合离子动量成像，在相位可控的ω-2ω强激光场（800和400 nm，强度为3.3×10^14 W/cm²）中研究乙腈二价阳离子内的分子内氢迁移。二体库仑爆炸通道CH₃CN²⁺→CH₃⁺+CN⁺沿激光偏振方向呈现出明显的相位依赖碎片不对称性，表明隧穿电离优先使乙腈二价阳离子的甲基指向激光电场振幅较小的一侧。单个氢原子迁移后发生的库仑爆炸通道CH₃CN²⁺→CH₂⁺+HCN⁺，其碎片不对称性显著降低。在氢迁移通道的不对称性中观察到明显的氘代效应，表明双色非对称激光场对乙腈二价阳离子内分子内氢迁移的方向性具有显著影响。
英文摘要
We investigate intramolecular hydrogen migration in acetonitrile dication in phase-controlled $ω$-$2ω$ intense laser fields (800 and 400 nm, 3.3$\times$10$^{14}$ W/cm$^2$) using three-dimensional coincidence ion momentum imaging. The two-body Coulomb explosion pathway, CH$_3$CN$^{2+}$ $\rightarrow$ CH$_3^+$ + CN$^+$, exhibits a clear phase-dependent fragment asymmetry along the laser polarization direction, showing that the tunnel ionization preferentially prepares the acetonitrile dication with the methyl group pointing toward the smaller amplitude side of the laser electric fields. The Coulomb explosion pathway occurring after the migration of a single hydrogen atom, CH$_3$CN$^{2+}$ $\rightarrow$ CH$_2^+$ + HCN$^+$, shows a pronounced reduction in the fragment asymmetry. A clear deuteration effect observed for the asymmetry of the hydrogen-migration pathway suggests that the two-color asymmetric laser field has a significant impact on directionality of intramolecular hydrogen migration in acetonitrile dication.
