Translational diffusion in supercooled water at and near the glass transition temperature -- 136 K
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| Formato: | Preprint |
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2025
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| author | Kimmel, Greg A. Dunlap, Megan K. Gurdumov, Kirill Smith, R. Scott Kringle, Loni Kay, Bruce D. |
| author_facet | Kimmel, Greg A. Dunlap, Megan K. Gurdumov, Kirill Smith, R. Scott Kringle, Loni Kay, Bruce D. |
| contents | The properties of amorphous solid water at and near the calorimetric glass transition temperature, $T_{g}$, of 136 K have been debated for years. One hypothesis is that water turns into a "true" liquid at $T_{g}$ (i.e., it becomes ergodic) and exhibits all the characteristics of an ergodic liquid, including translational diffusion. A competing hypothesis is that only rotational motion becomes active at $T_{g}$, while the "real" glass transition in water is at a considerably higher temperature. To address this dispute, we have investigated the diffusive mixing in nanoscale water films, with thicknesses up to ~100 nm, using infrared (IR) spectroscopy. The experiments used films that were composed of at least 90% $H_{2}O$ with $D_{2}O$ making up the balance and were conducted in conditions where H/D exchange was essentially eliminated. Because the IR spectra of multilayer $D_{2}O$ films (e.g., thicknesses of ~3 - 6 nm) embedded within thick $H_{2}O$ films are distinct from the spectrum of isolated $D_{2}O$ molecules within $H_{2}O$, the diffusive mixing of (initially) isotopically layered water films could be followed as a function of annealing time and temperature. The results show that water films with total thicknesses ranging from ~20 to 100 nm diffusively mixed prior to crystallization for temperatures between 120 and 144 K. The translational diffusion had an Arrhenius temperature dependence with an activation energy of 40.8 kJ/mol, which indicates that water at and near $T_{g}$ is a strong liquid. The measured diffusion coefficient at 136 K is 6.25 x 10$^{-21} m^{2}/s$. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2502_19627 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Translational diffusion in supercooled water at and near the glass transition temperature -- 136 K Kimmel, Greg A. Dunlap, Megan K. Gurdumov, Kirill Smith, R. Scott Kringle, Loni Kay, Bruce D. Soft Condensed Matter The properties of amorphous solid water at and near the calorimetric glass transition temperature, $T_{g}$, of 136 K have been debated for years. One hypothesis is that water turns into a "true" liquid at $T_{g}$ (i.e., it becomes ergodic) and exhibits all the characteristics of an ergodic liquid, including translational diffusion. A competing hypothesis is that only rotational motion becomes active at $T_{g}$, while the "real" glass transition in water is at a considerably higher temperature. To address this dispute, we have investigated the diffusive mixing in nanoscale water films, with thicknesses up to ~100 nm, using infrared (IR) spectroscopy. The experiments used films that were composed of at least 90% $H_{2}O$ with $D_{2}O$ making up the balance and were conducted in conditions where H/D exchange was essentially eliminated. Because the IR spectra of multilayer $D_{2}O$ films (e.g., thicknesses of ~3 - 6 nm) embedded within thick $H_{2}O$ films are distinct from the spectrum of isolated $D_{2}O$ molecules within $H_{2}O$, the diffusive mixing of (initially) isotopically layered water films could be followed as a function of annealing time and temperature. The results show that water films with total thicknesses ranging from ~20 to 100 nm diffusively mixed prior to crystallization for temperatures between 120 and 144 K. The translational diffusion had an Arrhenius temperature dependence with an activation energy of 40.8 kJ/mol, which indicates that water at and near $T_{g}$ is a strong liquid. The measured diffusion coefficient at 136 K is 6.25 x 10$^{-21} m^{2}/s$. |
| title | Translational diffusion in supercooled water at and near the glass transition temperature -- 136 K |
| topic | Soft Condensed Matter |
| url | https://arxiv.org/abs/2502.19627 |