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No fragile-to-strong crossover in LiCl-H2O solution
Masahiro Nakanishi1, Philip Griffin, Eugene Mamontov
1Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA.
The Journal of Chemical Physics
|April 3, 2012
Summary
Water dynamics in the "no man's land" are clarified. Studies of aqueous lithium chloride (LiCl) solutions show no fragile-to-strong crossover (FSC), but reveal an excess wing indicating localized relaxation.
Area of Science:
- Physical Chemistry
- Chemical Physics
- Materials Science
Background:
- Water dynamics, particularly in the supercooled regime (200-230 K), are poorly understood.
- Aqueous solutions, like LiCl, serve as models for bulk water behavior.
Purpose of the Study:
- To investigate the dynamics of water in aqueous LiCl solutions.
- To determine if a fragile-to-strong crossover (FSC) exists in these solutions.
Main Methods:
- Broadband dielectric spectroscopy.
- Light scattering spectroscopy.
- Analysis of experimental data combined with literature.
Main Results:
- No evidence of a fragile-to-strong crossover (FSC) in structural relaxation or translational motions.
- Observation of an 'excess wing' on the high-frequency side of the structural relaxation peak.
- Identification of localized relaxation processes contributing to the excess wing.
Conclusions:
- The dynamics of aqueous solutions do not exhibit a fragile-to-strong crossover (FSC) around 200-230 K.
- The excess wing is a key feature, suggesting localized dynamics are significant in this temperature range.
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