5:15 PM - 7:15 PM
[MIS13-P06] Response of homoimmiscible water at water/basal plane of ice Ih interface on overpressure
Keywords:Interface, water, Ice, Homoimmiscible water
Ice formation from water strongly impacts on the global environment on the Earth. It is significant to elucidate the mechanism of crystallization of ice from water. Crystallization of ice from water is strongly governed by the interfacial phenomena between water and ice. Therefore, it is crucial to understand the non-equilibrium ice-water interfacial phenomena. However, the details in the interfacial phenomena are still unclear because of the difficulty in experimental approach. Thus, numerical investigations based on molecular dynamics (MD) simulations have significantly preceded experimental investigations nowadays. MD simulations facilitated an opportunity for researchers to strongly focus on “microscopic” interfacial phenomena.
Amid this situation, we recently discovered, by conventional in-situ optical microscopy, that unknown water separated from the surrounding bulk water macroscopically appears at the interfaces between water and (high-pressure) ices.[2-5] We named the unknown waters “homoimmiscible water”. These discoveries should provide novel insights on ice/water interfacial phenomena because macroscopic views have been lacked in the research on ice/water interface. The elucidation of the dynamics, local structures, physicochemical properties, and thermodynamic characteristics of homoimmiscible water has the potential to open new avenues for understanding ice/water interfacial phenomena. However, systematic studies of homoimmiscible waters are still lacking.
Here, we systematically investigated the influence of the magnitude of the applied overpressure on the formation and dynamics of homoimmiscible water at the interface between water and basal plane of a single crystal ice by using a dynamic sapphire anvil cell (d-SAC), which can electrically regulate the magnitude of the overpressure.[6]
A single crystal of ice Ih was obtained so that its basal plane becomes perpendicular to the observation direction by repeatedly pressurizing and depressurizing ultrapure water around approximately 107 MPa using the d-SAC at -10oC. The ice crystal was melted by applying the overpressures of 0.4, 0.7, 1.0, 1.4, 1.6, 2.0 and 2.3 GPa, which corresponds to the thermodynamic droving forces of 1.2 × 10-21, 2.5 × 10-21, 3.7 × 10-21, 4.9 × 10-21, 6.2 × 10-21, 7.2 × 10-21 and 8.7 × 10-21 J, respectively. The formation and dynamics of homoimmiscible water were observed in-situ using a Fizeau-type laser interferometric microscopy in the low-temperature room kept at -10oC.
In-situ observations revealed that concentric interferometric interference fringes which were absent before the compression appeared inside of the circle of the melting circular disk-like ice/water interface after the compression of 2.3 GPa [Fig. 1 (a)]. The appearance of the new interference fringes indicates that hommoimmiscible water appeared at the interface. After the concentric interference fringes moved like a ripple wave, the concentric interference fringes shrunk toward the center of the concentric fringes like the shrinkage of a liquid droplet. The droplet-like homoimmiscible water once shrunk and expanded after forming entirely on the basal plane of the ice. This droplet-like bulky homoimmiscible water changed to a thin layer after the expansion. The expanded thin layer of the homoimmiscible water shrunk again and finally disappeared. This two-step shrinkage of the homoimmiscible water, i.e., the shrinkage of the droplet-like bulky one followed by the shrinkage of the thin layered one, was observed in the range of overpressure from 1.4 to 2.3 GPa. On the other hand, in the overpressure range from 0.4 to 1.0 GPa, only the shrinkage of the thin layered homoimmiscible water was observed [Fig. 1 (b)]. Namely, homoimmiscible water was found to show variety in its morphology depending on the magnitude of overpressure.
The observed interference fringe allowed us to estimate the thickness of the homoimmiscible water. The thickness of the homoimmiscible water was found to be proportional to the magnitude of the overpressure (Fig. 2). This indicates that the volume of homoimmiscible water has a constant relationship with the magnitude of thermodynamic driving force for phase transformation. This discovery provides insights on the fundamental question whether homoimmiscible water is a thermodynamic phase.
[1] Y. Kim et al., Proc. Natl. Acad. Sci. U.S.A. 2019, 116, 8679.
[2] H. Niinomi et al., J. Phys. Chem. Lett. 2020, 11, 6779.
[3] H. Niinomi et al., J. Phys. Chem. Lett. 2022, 13, 4251.
[4] H. Niinomi et al., Sci. Rep. 2023, 13, 16227.
[5] H. Niinomi et al., J. Phys. Chem. Lett. 2024, 15, 659.
[6] H. Niinomi et al., J. Phys. Chem. C 2024, 128, 15649.
Amid this situation, we recently discovered, by conventional in-situ optical microscopy, that unknown water separated from the surrounding bulk water macroscopically appears at the interfaces between water and (high-pressure) ices.[2-5] We named the unknown waters “homoimmiscible water”. These discoveries should provide novel insights on ice/water interfacial phenomena because macroscopic views have been lacked in the research on ice/water interface. The elucidation of the dynamics, local structures, physicochemical properties, and thermodynamic characteristics of homoimmiscible water has the potential to open new avenues for understanding ice/water interfacial phenomena. However, systematic studies of homoimmiscible waters are still lacking.
Here, we systematically investigated the influence of the magnitude of the applied overpressure on the formation and dynamics of homoimmiscible water at the interface between water and basal plane of a single crystal ice by using a dynamic sapphire anvil cell (d-SAC), which can electrically regulate the magnitude of the overpressure.[6]
A single crystal of ice Ih was obtained so that its basal plane becomes perpendicular to the observation direction by repeatedly pressurizing and depressurizing ultrapure water around approximately 107 MPa using the d-SAC at -10oC. The ice crystal was melted by applying the overpressures of 0.4, 0.7, 1.0, 1.4, 1.6, 2.0 and 2.3 GPa, which corresponds to the thermodynamic droving forces of 1.2 × 10-21, 2.5 × 10-21, 3.7 × 10-21, 4.9 × 10-21, 6.2 × 10-21, 7.2 × 10-21 and 8.7 × 10-21 J, respectively. The formation and dynamics of homoimmiscible water were observed in-situ using a Fizeau-type laser interferometric microscopy in the low-temperature room kept at -10oC.
In-situ observations revealed that concentric interferometric interference fringes which were absent before the compression appeared inside of the circle of the melting circular disk-like ice/water interface after the compression of 2.3 GPa [Fig. 1 (a)]. The appearance of the new interference fringes indicates that hommoimmiscible water appeared at the interface. After the concentric interference fringes moved like a ripple wave, the concentric interference fringes shrunk toward the center of the concentric fringes like the shrinkage of a liquid droplet. The droplet-like homoimmiscible water once shrunk and expanded after forming entirely on the basal plane of the ice. This droplet-like bulky homoimmiscible water changed to a thin layer after the expansion. The expanded thin layer of the homoimmiscible water shrunk again and finally disappeared. This two-step shrinkage of the homoimmiscible water, i.e., the shrinkage of the droplet-like bulky one followed by the shrinkage of the thin layered one, was observed in the range of overpressure from 1.4 to 2.3 GPa. On the other hand, in the overpressure range from 0.4 to 1.0 GPa, only the shrinkage of the thin layered homoimmiscible water was observed [Fig. 1 (b)]. Namely, homoimmiscible water was found to show variety in its morphology depending on the magnitude of overpressure.
The observed interference fringe allowed us to estimate the thickness of the homoimmiscible water. The thickness of the homoimmiscible water was found to be proportional to the magnitude of the overpressure (Fig. 2). This indicates that the volume of homoimmiscible water has a constant relationship with the magnitude of thermodynamic driving force for phase transformation. This discovery provides insights on the fundamental question whether homoimmiscible water is a thermodynamic phase.
[1] Y. Kim et al., Proc. Natl. Acad. Sci. U.S.A. 2019, 116, 8679.
[2] H. Niinomi et al., J. Phys. Chem. Lett. 2020, 11, 6779.
[3] H. Niinomi et al., J. Phys. Chem. Lett. 2022, 13, 4251.
[4] H. Niinomi et al., Sci. Rep. 2023, 13, 16227.
[5] H. Niinomi et al., J. Phys. Chem. Lett. 2024, 15, 659.
[6] H. Niinomi et al., J. Phys. Chem. C 2024, 128, 15649.