Claus Jordan A, Melosso Mattia, Maillard Agathe, Bizzocchi Luca, Barone Vincenzo, Puzzarini Cristina
Dipartimento di Chimica "Giacomo Ciamician", Università di Bologna, Via F. Selmi 2, 40126 Bologna, Italy.
INSTM, 50121 Firenze, Italy.
ACS Earth Space Chem. 2025 Apr 29;9(5):1267-1276. doi: 10.1021/acsearthspacechem.5c00067. eCollection 2025 May 15.
Ethylene glycol (CHOH-CHOH) is an abundant "complex organic molecule" (COM) detected in different astronomical objects, but the steps of its interstellar synthesis are not yet fully understood. In this respect, the observation of deuterated isotopologues could offer insights into its formation mechanism as well as into its chemical evolution in space. Such observations, however, require detailed spectroscopic knowledge of their rotational features. Here, we present an extensive analysis of the rotational spectrum of oxygen-deuterated ethylene glycol, including the singly and doubly deuterated forms. The new measurements, carried out between 75 and 450 GHz, significantly expand the spectroscopic knowledge of the ' conformers of the CHOH-CHOD, CHOD-CHOH, and CHOD-CHOD species. We also report, for the first time, the laboratory identification of the ' conformers of the two mono-deuterated species. Our results reveal previously unobserved perturbations arising from the interaction between CHOH-CHOD and CHOD-CHOH, which has been modeled by including Coriolis coupling and Fermi constants in the Hamiltonian and allowed the accurate determination of the energy difference among them. Additionally, we observed significant anomalies in the spectrum of the doubly deuterated species, which seem to be caused by accidental degeneracies between the levels of the two tunneling substates. Despite the complexity and difficulties, the improved spectroscopic parameters derived from our analyses provide a solid base for future interstellar searches of deuterated ethylene glycol, enhancing our understanding of the evolution of COMs in the interstellar medium.
乙二醇（CHOH-CHOH）是在不同天体中检测到的一种丰富的“复杂有机分子”（COM），但其星际合成步骤尚未完全了解。在这方面，对氘代同位素异构体的观测可以深入了解其形成机制以及在太空中的化学演化。然而，此类观测需要对其转动特征有详细的光谱知识。在此，我们对氧代氘代乙二醇的转动光谱进行了广泛分析，包括单氘代和双氘代形式。在75至450吉赫兹之间进行的新测量显著扩展了CHOH-CHOD、CHOD-CHOH和CHOD-CHOD物种的'构象异构体的光谱知识。我们还首次报告了两种单氘代物种的'构象异构体的实验室鉴定。我们的结果揭示了CHOH-CHOD和CHOD-CHOH之间相互作用产生的先前未观察到的微扰，通过在哈密顿量中纳入科里奥利耦合和费米常数对其进行了建模，并准确确定了它们之间的能量差。此外，我们在双氘代物种的光谱中观察到了显著异常，这似乎是由两个隧穿子态的能级之间的偶然简并引起的。尽管存在复杂性和困难，但我们分析得出的改进光谱参数为未来星际搜索氘代乙二醇提供了坚实基础，增强了我们对星际介质中COM演化的理解。
