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Abstract Recent experiments and theoretical studies strongly indicate that water exhibits a liquid-liquid phase transition (LLPT) in the supercooled domain. An open question is how the LLPT of water can affect the properties of aqueous solutions. Here, we study the structural and thermodynamic properties of supercooled glycerol-water microdroplets at dilute conditions (χg = 3.2% glycerol mole fraction). The combination of rapid evaporative cooling with femtosecond X-ray scattering allows us to outrun crystallization and gain access to the deeply supercooled regime down toT = 229.3 K. We find that the density fluctuations of the glycerol-water solution or, equivalently, its isothermal compressibility,κT, increases upon cooling. This is confirmed by molecular dynamics simulations, which indicate that the presence of glycerol shifts the temperature of maximumκTfromT = 230 K in pure water down toT = 223 K in the solution. Our findings elucidate the interplay between the complex behavior of water, including its LLPT, and the properties of aqueous solutions at low temperatures, which can have practical consequences in cryogenic biological applications and cryopreservation techniques.
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Digital Holography Interferometry for Refractive Index Characterization and Temperature Mapping of Aqueous Solutions at Supercooled Temperatures
Abstract Cryopreservation of biological matter nigh‐universally requires cooling organic aqueous solutions through the metastable supercooled temperature regime. However, for many solutions of interest, very little thermophysical data exists at these temperatures, hampering the meaningful design of cryopreservation protocols or interrogation of cryopreservation processes. Digital holography interferometry (DHI) has recently emerged as a promising technique for measuring and characterizing the physical properties of liquids. Herein, DHI is proposed as a thermal imaging and characterization tool capable of measuring optical properties, such as temperature‐dependent refractive index, and providing high‐resolution two‐dimensional (2D) visualization of temperature distribution in the supercooling regime. This approach overcomes the limitations of traditional techniques such as thermocouples and thermal cameras. This work describes a DHI platform instrumented with a custom thermoelectric supercooling apparatus, demonstrates 2D temperature mapping in the supercooled regime, and measures the refractive index of water, 10% dimethyl sulfoxide (DMSO), and 49% DMSO solutions at sub‐273 K temperatures. Overall, DHI is demonstrated as a noninvasive optical tool with high resolution for studying supercooled liquids, potentially enhancing cryopreservation protocols and providing new thermo‐optical information on cryoprotective agents at sub‐273 K temperatures.
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- Award ID(s):
- 1941543
- PAR ID:
- 10665221
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Laser & Photonics Reviews
- Volume:
- 19
- Issue:
- 9
- ISSN:
- 1863-8880
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.1002/lpor.202400921
