We present the first observation of vibrational transitions in the [H₃O]⁻ anion, an intermediate in the anion–molecule reaction of water, H₂O, and hydride, H^–, using a laser-induced isotopic H/D exchange reaction action spectroscopy scheme applied to anions. The observed bands are assigned as the fundamental and first overtone of the H₂O–H^– vibrational stretching mode, based on anharmonic calculations within the vibrational perturbation theory and vibrational configuration interaction. Although the D₂O·D^– species has the lowest energy, our experiments confirm the D₂O·H^– isotope to be a sink of the H/D exchange reaction. Ab initio calculations corroborate that the formation of D₂O·H^– is favored, as the zero-point-energy difference is larger between D₂ and H₂ than between D₂O·H^– and D₂O·D^–.

中文翻译：

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中红外作用光谱探测 [H3O]− 阴离子的零点能量驱动同位素交换


我们首次观察到 [H ₃ O] ⁻ 阴离子的振动跃迁，阴离子是水阴离子-分子反应的中间体，H ₂ O和氢化物 H ^– ，使用应用于阴离子的激光诱导同位素 H/D 交换反应作用光谱方案。基于振动扰动理论和振动构型相互作用中的非调和计算，观察到的谱带被指定为 H ₂ O–H ^– 振动拉伸模式的基本泛音和第一泛音。虽然 D ₂ O·D ^– 物种具有最低的能量，但我们的实验证实 D ₂ O·H ^– 同位素是H/D交换反应的汇。从头计算证实，D ₂ O·H ^– 的形成是有利的，因为 D ₂ 和 H 之间的零点能量差较大。 ₂ 比 D ₂ O·H ^– 和 D ₂ O·D ^– 之间的值要高。