Chen, LigangRen, GuanhuaLiu, LiyuanGuo, PanWan, EndongZhou, LuZhu, ZhongjieZhang, JianbingYang, BinZhang, WentaoLi, YanfengZhang, WeiliGao, YiZhao, HongweiHan, Jiaguang2020-09-012020-09-012020-08-06L.Chen, G.Ren, L.Liu, P.Guo, E.Wang, L.Zhou, Z.Zhu, J.Zhang, B.Yang, W.Zhang, Y.Li, W.Zhang, Y.Gao, H.Zhao, J.Han (2020). Terahertz Signatures of Hydrate Formation in Alkali Halide Solutions. Journal of Physical Chemistry Letters, 11(17), 7146-7152.10.1021/acs.jpclett.0c02046http://hdl.handle.net/10034/623616This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of Physical Chemistry Letters, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acs.jpclett.0c02046.We systematically studied the ability of 20 alkali halides to form solid hydrates in the frozen state from their aqueous solutions by terahertz time-domain spectroscopy combined with density functional theory (DFT) calculations. We experimentally observed the rise of new terahertz absorption peaks in the spectral range of 0.3-3.5 THz in frozen alkali halide solutions. The DFT calculations prove that the rise of observed new peaks in solutions containing Li+, Na+ or F‾ ions indicates the formation of salt hydrates, while that in other alkali halide solutions is caused by the splitting phonon modes of the imperfectly crystallized salts in ice. As a simple empirical rule, the correlation between the terahertz signatures and the ability of 20 alkali halides to form a hydrate has been established.CC0 1.0 Universalhttps://creativecommons.org/licenses/by-nc-nd/4.0/Article1948-7185Journal of Physical Chemistry Letters