Cole William T S, Fellers Raymond S, Viant Mark R, Saykally Richard J
Department of Chemistry, University of California, Berkeley, California 94720, USA.
J Chem Phys. 2017 Jan 7;146(1):014306. doi: 10.1063/1.4973418.
Hydrogen bonds in solid and liquid water are formed and broken via librational vibrations, hence characterizing the details of these motions is vital to understanding these important dynamics. Here we report the measurement and assignment of 875 transitions comprising 6 subbands originating from out-of-plane librational transitions of the water pentamer-d near 512 cm. The precisely measured (ca. 1 ppm) transitions reveal bifurcation splittings of ∼1884 MHz, a ∼4000× enhancement over ground state splittings and 100× greater than predicted by theory. The pentamer is thus the third water cluster to display greatly enhanced bifurcation tunneling upon single quantum excitation of librational vibrations. From the intensity pattern of the observed transitions, the mechanism of bifurcation is established by comparison with theoretical predictions.
固态和液态水中的氢键通过摆动振动形成和断裂，因此表征这些运动的细节对于理解这些重要动力学至关重要。在此，我们报告了对875个跃迁的测量和归属，这些跃迁包括6个源自水五聚体-d在512 cm附近的面外摆动跃迁的子带。精确测量（约1 ppm）的跃迁揭示了约1884 MHz的分支分裂，比基态分裂增强了约4000倍，比理论预测大100倍。因此，五聚体是第三个在摆动振动单量子激发时显示出大大增强的分支隧穿的水簇。根据观察到的跃迁的强度模式，通过与理论预测进行比较确定了分支机制。
