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Chen L, Ren G, Liu L, Guo P, Wang E, Zhou L, Zhu Z, Zhang J, Yang B, Zhang W, Li Y, Zhang W, Gao Y, Zhao H, Han J. Terahertz Signatures of Hydrate Formation in Alkali Halide Solutions. J Phys Chem Lett 2020; 11:7146-7152. [PMID: 32787323 DOI: 10.1021/acs.jpclett.0c02046] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
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.
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Affiliation(s)
- Ligang Chen
- Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072, People's Republic of China
- Shanghai Advanced Research Institute Zhangjiang Lab, Chinese Academy of Sciences, Shanghai 201210, China
| | - Guanhua Ren
- Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072, People's Republic of China
- Shanghai Advanced Research Institute Zhangjiang Lab, Chinese Academy of Sciences, Shanghai 201210, China
| | - Liyuan Liu
- Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072, People's Republic of China
| | - Pan Guo
- Division of Interfacial Water and Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
| | - Endong Wang
- Division of Interfacial Water and Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
| | - Lu Zhou
- Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072, People's Republic of China
| | - Zhongjie Zhu
- Division of Interfacial Water and Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
| | - Jianbing Zhang
- Shanghai Advanced Research Institute Zhangjiang Lab, Chinese Academy of Sciences, Shanghai 201210, China
- Division of Interfacial Water and Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
| | - Bin Yang
- Faculty of Science and Engineering, University of Chester, Thornton Science Park, Chester, U.K. CH2 4NU
| | - Wentao Zhang
- Guangxi Key Laboratory of Optoelectronic Information Processing, Guilin University of Electronic Technology, Guilin 541004, China
| | - Yanfeng Li
- Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072, People's Republic of China
| | - Weili Zhang
- Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072, People's Republic of China
- School of Electrical and Computer Engineering, Oklahoma State University, Stillwater, Oklahoma 74078, United States
| | - Yi Gao
- Shanghai Advanced Research Institute Zhangjiang Lab, Chinese Academy of Sciences, Shanghai 201210, China
- Division of Interfacial Water and Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
| | - Hongwei Zhao
- Shanghai Advanced Research Institute Zhangjiang Lab, Chinese Academy of Sciences, Shanghai 201210, China
- Division of Interfacial Water and Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
| | - Jiaguang Han
- Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072, People's Republic of China
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Hutzler D, Stallhofer K, Kienberger R, Riedle E, Iglev H. Icelike Vibrational Properties of Strong Hydrogen Bonds in Hydrated Lithium Nitrate. J Phys Chem A 2020; 124:5784-5789. [PMID: 32574493 DOI: 10.1021/acs.jpca.0c01588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The hydrogen bond network accounts for many of the extraordinary physical properties of liquid water and ice. Its vibrational dynamics are quite complex in their entirety but can be accessed in detail by investigating small groups of only a few water molecules. Here, aqueous salt hydrates turned out to be an exceptional model system for water molecules arranged in well-defined geometrical structures that can be accessed by means of femtosecond spectroscopy of the OH stretching vibration. In this study, we find striking resemblance between the vibrational properties of three water molecules connected via strong hydrogen bonds in the trihydrate of LiNO3 and those of ordinary ice Ih. As in ice, the vibrations of the hydrate water molecules show ultrafast excited state dynamics that are strongly accelerated when proceeding from deuterated to neat H2O samples. The latter is analyzed by means of an additional relaxation channel that is due to Fermi resonance between the OH stretching vibration and the bend overtone accompanied by delocalization of the vibration over neighboring water molecules in the H2O species. Moreover, in the hydrate and ice samples severe spectral broadening is examined when comparing fundamental and excited state absorption bands. Here, proton delocalization along the strong hydrogen bonds is given as a possible underlying mechanism.
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Affiliation(s)
- Daniel Hutzler
- Physik-Department E11, Technische Universität München, James-Franck-Strasse 1, 85748 Garching, Germany
| | - Klara Stallhofer
- Physik-Department E11, Technische Universität München, James-Franck-Strasse 1, 85748 Garching, Germany
| | - Reinhard Kienberger
- Physik-Department E11, Technische Universität München, James-Franck-Strasse 1, 85748 Garching, Germany
| | - Eberhard Riedle
- Lehrstuhl für BioMolekulare Optik, Ludwig-Maximilians-Universität München, Oettingenstraßsse 67, 80538 München, Germany
| | - Hristo Iglev
- Physik-Department E11, Technische Universität München, James-Franck-Strasse 1, 85748 Garching, Germany
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