We investigate reactions between laser-cooled Be⁺ ions and room-temperature water molecules using an integrated ion trap and high-resolution time-of-flight mass spectrometer. This system allows simultaneous measurement of individual reaction rates that are resolved by reaction product. The rate coefficient of the Be⁺(²S_1/2) + H₂O → BeOH⁺ + H reaction is measured for the first time and is found to be approximately two times smaller than predicted by an ion–dipole capture model. Zero-point-corrected quasi-classical trajectory calculations on a highly accurate potential energy surface for the ground electronic state reveal that the reaction is capture-dominated, but a submerged barrier in the product channel lowers the reactivity. Furthermore, laser excitation of the ions from the ²S_1/2 ground state to the ²P_3/2 state opens new reaction channels, and we report the rate and branching ratio of the Be⁺(²P_3/2) + H₂O → BeOH⁺ + H and H₂O⁺ + Be reactions. The excited-state reactions are nonadiabatic in nature.

中文翻译：

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水和激光冷却的Be ⁺离子之间反应的光学控制

我们使用集成的离子阱和高分辨率飞行时间质谱仪研究激光冷却的Be ⁺离子与室温水分子之间的反应。该系统允许同时测量由反应产物分辨出的各个反应速率。Be ⁺（² S _1/2）+ H ₂ O→BeOH ⁺的比率系数首次测量+ H反应，发现其大约比离子偶极子捕获模型预测的小两倍。在基态电子态的高精度势能表面上进行零点校正的准经典轨迹计算表明，该反应是俘获为主的，但是产物通道中的浸没势垒降低了反应性。此外，离子从² S _1/2基态到² P _3/2态的激光激发开辟了新的反应通道，我们报道了Be ⁺（² P _3/2）+ H的速率和支化比₂ O→BeOH ⁺ + H和H₂ O ⁺ +是反应。激发态反应本质上是非绝热的。