Abstract Rotational transitions of gauche-acetone cyanohydrin are measured in the microwave range between 5 and 23 GHz. Results from quantum chemical calculations indicate that the hydrogen atom of the hydroxyl group undergoes a tunneling motion connecting two equivalent structures. The observed signals are assigned to the two lowest tunneling substates 0 + and 0 - , which belong to either a- or c-type transitions exhibiting Coriolis splittings of a few MHz. Additional hyperfine structure arises from the quadrupole coupling 14N nucleus. The energy separation Δ E between the 0 + and 0 - states is predicted to be around 50 GHz. The molecular structure and internal dynamics are discussed in terms of their spectral signatures.

中文翻译：

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丙酮氰醇旋转光谱中的质子反转隧道

摘要 在 5 至 23 GHz 的微波范围内测量了焦糖丙酮氰醇的旋转跃迁。量子化学计算的结果表明，羟基的氢原子经历了连接两个等效结构的隧穿运动。观察到的信号被分配给两个最低的隧道子状态 0 + 和 0 - ，它们属于表现出几 MHz 科里奥利分裂的 a 型或 c 型跃迁。额外的超精细结构来自四极耦合 14N 核。0 + 和 0 - 状态之间的能量分离 Δ E 预计约为 50 GHz。分子结构和内部动力学根据它们的光谱特征进行讨论。