Wespiser Clément, Putaud Thomas, Kalugina Yulia, Soldera Armand, Roy Pierre-Nicholas, Michaut Xavier, Ayotte Patrick
Département de Chimie, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada.
Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
J Chem Phys. 2022 Feb 21;156(7):074304. doi: 10.1063/5.0079565.
Confinement effects on the ro-translational (RT) dynamics of water, trapped in rare gas matrices or within endofullerenes (i.e., HO@C), can be experimentally assessed using rotationally resolved far-infrared, or mid-infrared, spectroscopy [Putaud et al., J. Chem. Phys. 156, 074305 (2022) (Paper II)]. The confined rotor model is used here to reveal how the quantized rotational and frustrated translational energy levels of confined water interact and mix by way of the confinement-induced rotation-translation coupling (RTC). An eccentric but otherwise isotropic 3D harmonic effective potential is used to account for confinement effects, thereby allowing the dependence of the magnitude of the RTC on the topology of the model confinement potential, the resulting intricate mixing schemes, and their impact on the RT energy levels to be examined in detail. The confined rotor model thus provides a convenient framework to investigate the matrix and isotope effects on the RT dynamics of water under extreme confinement probed spectroscopically, thereby potentially providing insight into the mechanisms and rates for ortho-HO ↔ para-HO nuclear spin isomer interconversion in confined water.
利用转动分辨的远红外或中红外光谱 [Putaud等人，《化学物理杂志》156, 074305 (2022) (论文II)]，可以通过实验评估限制在稀有气体基质或内嵌富勒烯（即HO@C）中的水的转动平移（RT）动力学的限制效应。这里使用受限转子模型来揭示受限水的量子化转动和平移受阻能级如何通过限制诱导的转动-平移耦合（RTC）相互作用和混合。使用一个偏心但各向同性的三维谐振子有效势来考虑限制效应，从而能够详细研究RTC的大小对模型限制势拓扑结构的依赖性、由此产生的复杂混合方案及其对RT能级的影响。因此，受限转子模型提供了一个方便的框架，用于研究光谱探测的极端限制条件下水的RT动力学的基质和同位素效应，从而有可能深入了解受限水中正-水 ↔ 仲-水核自旋异构体相互转化的机制和速率。
