Maithani Sanchi, Panda Biswajit, Maity Abhijit, Pradhan Manik
Department of Chemical, Biological and Macromolecular Sciences , S. N. Bose National Centre for Basic Sciences , Salt Lake, JD Block , Sector III, Kolkata 700106 , India.
Technical Research Centre , S. N. Bose National Centre for Basic Sciences , Salt Lake, JD Block , Sector III, Kolkata 700106 , India.
J Phys Chem A. 2020 Feb 13;124(6):1104-1111. doi: 10.1021/acs.jpca.9b11401. Epub 2020 Feb 3.
The underlying mechanisms of the triple-oxygen (O, O, and O) isotopic content of deuterated (D) isotopologues of water in H-D exchange reactions in the gas phase remain elusive. Herein, we have demonstrated a high-resolution gas-phase spectral analysis of doubly (DO) and singly (HDO) deuterated isotopologues of water in the region around 7.8 μm using quantum cascade laser-based cavity ring-down spectroscopy. Isotopic fractionations among doubly and singly deuterated species of water, DO, HDO, HDO, and HDO, in the gas phase were carried out by probing the fundamental and hot band transitions in the ν (bending) mode of DO and the fundamental ν transitions for the other water isotopes. We subsequently investigated the fractionations of different D-enriched water isotopologues for the H-D exchange reaction using various mixtures of DO in HO. We explored the potential role of triple-oxygen isotopic contents through enrichments and depletions of HDO, HDO, and HDO, involved in the H-D reaction. Our first clear, direct, and quantitative experimental evidence reveals a new picture of gas-phase isotopic fractionation chemistry in a mixture of light and heavy water (HO-DO).
气相中氢氘（H-D）交换反应中氘化（D）水同位素分子的三重氧（O、O和O）同位素含量的潜在机制仍然难以捉摸。在此，我们利用基于量子级联激光器的光腔衰荡光谱技术，对7.8μm附近区域的水的双氘代（DO）和单氘代（HDO）同位素分子进行了高分辨率气相光谱分析。通过探测DO的ν（弯曲）模式中的基频和热带跃迁以及其他水同位素的基频ν跃迁，对气相中双氘代和单氘代水物种（DO、HDO、HDO和HDO）之间的同位素分馏进行了研究。随后，我们使用HO中DO的各种混合物，研究了不同富含D的水同位素分子在H-D交换反应中的分馏情况。我们通过参与H-D反应的HDO、HDO和HDO的富集和贫化，探索了三重氧同位素含量的潜在作用。我们首个清晰、直接且定量的实验证据揭示了轻水和重水（HO-DO）混合物中气相同位素分馏化学的新图景。
