The fully state-selected reactions between H₂⁺ molecules in the X^{+ 2}Σ_g⁺(v⁺ = 0, N⁺ = 0) state and HD molecules in the X ¹Σ_g⁺(v = 0, J = 0) state forming H₃⁺ + D and H₂D⁺ + H have been studied at collision energies E_coll between 0 and k_B·30 K with a resolution of about 75 mK at the lowest energies. H₂ molecules in a supersonic beam were prepared in Rydberg-Stark states with principal quantum number n = 27 and merged with a supersonic beam of ground-state HD molecules using a curved surface-electrode Rydberg-Stark decelerator and deflector. The reaction between H₂⁺ and HD was studied within the orbit of the Rydberg electron to avoid heating of the ions by stray electric fields. The reaction was observed for well-defined and adjustable time intervals, called reaction-observation windows, between two electric-field pulses. The first pulse swept all ions away from the reaction volume and its falling edge defined the beginning of the reaction-observation window. The second pulse extracted the product ions toward a charged-particle detector located at the end of a time-of-flight tube and its rising edge defined the end of the reaction-observation window. Monitoring and analysing the time-of-flight distributions of the H₃⁺ and H₂D⁺ products in dependence of the duration of the reaction-observation window enabled us to obtain information on the kinetic-energy distribution of the product ions and determine branching ratios of the H₃⁺ + D and H₂D⁺ + H reaction channels. The mean product-kinetic-energy release is 0.46(5) eV, representing 27(3)% of the available energy, and the H₃⁺ + D product branching ratio is 0.225(20). The relative reaction rates correspond closely to Langevin capture rates down to the lowest energies probed experimentally (≈k_B·50 mK).

中文翻译：

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低碰撞能量下的H2 + HD反应：H3 + / H2D +支化比和产物动力学能量分布

h的完全状态选择的反应_2个⁺在X分子^{+ 2} Σ_克⁺（v ⁺ = 0，Ñ ⁺ = 0）在X状态和HD分子¹ Σ_克⁺（v = 0，Ĵ = 0）研究了在碰撞能量E _coll在0至k _B ·30 K之间时形成H ₃ ⁺ + D和H ₂ D ⁺ + H的状态，在最低能量下分辨率约为75 mK。高₂超声束中的分子以主量子数n = 27的Rydberg-Stark状态制备，并使用曲面电极Rydberg-Stark减速器和偏转器与基态HD分子的超声束合并。H ₂ ⁺之间的反应为了避免杂散电场加热离子，对HD进行了Rydberg电子轨道研究。在两个电场脉冲之间以明确定义且可调的时间间隔（称为反应观察窗口）观察反应。第一个脉冲将所有离子从反应体积中清除，其下降沿定义了反应观察窗口的起点。第二个脉冲将产物离子引向位于飞行时间管末端的带电粒子检测器，其上升沿定义了反应观察窗口的末端。监视和分析H ₃ ⁺和H ₂ D ⁺的飞行时间分布取决于反应观察窗口持续时间的产物，使我们能够获得有关产物离子的动能分布的信息，并确定H ₃ ⁺ + D和H ₂ D ⁺ + H反应通道的分支比。产物的平均动能释放为0.46（5）eV，占可用能量的27（3）％，H ₃ ⁺ + D产物的分支比为0.225（20）。相对反应速率密切地对应于郎之万捕获率下降到最低能量探测实验（≈ ķ_乙·50 MK）。