Possible Anomaly in the Surface Tension of Supercooled Water: New Experiments at Extreme Supercooling down to −31.4 °C

Abstract

The surface tension of water is suspected to show a substantial increase at low temperatures, which is considered to be one of the many anomalies of water. The second inflection point (SIP) anomaly, originally claimed to be at around −8 °C, was experimentally refuted down to −25 °C by Hrubý et al. ( J. Phys. Chem. Lett. 2014, 5, 425–428). Recent molecular simulations predict the SIP anomaly near or even below the homogeneous freezing limit of around −38 °C. To contribute to an ongoing discussion about the SIP anomaly, new experiments focused on extreme levels of supercooling were carried out in this study. Unique experimental data down to −31.4 °C were collected using two measuring techniques based on the capillary rise method. A significant deviation from the extrapolated IAPWS formulation R1-76(2014) for surface tension of ordinary water was detected below −20 °C. Contrary to previous data, new experiments provide room for an anomaly in the course of surface tension in the deeply supercooled region.

High-density liquid (HDL) adsorption at the supercooled water/vapor interface and its possible relation to the second surface tension inflection point

“…2, where we also report the simulation data of Wang and coworkers 16 and the experimental points from Ref. 14 , for comparison. The departure from the IAPWS equation shows the presence of an anomalous rise of the surface tension at low temperatures, implying the presence of an inflection point.…”

“…However, whether this agree- ment can continue deeper in the supercooled regime is controversial, as measurements of surface tension become very involved 13 . A recent experimental study 14 measured the surface tension of water down to about 241 K using the capillary rise method and reported a deviation from the IAPWS equation that opens the possibility of the existence of a second inflection point. Computational studies support the appearance of the second inflection point for several water models, including SPC/E 15,16 , TIP4P/2005 16 and WAIL 17 .…”

Interfacial Properties of Fluids Exhibiting Liquid Polyamorphism and Water-Like Anomalies

“…The possibility of anomalous behavior of the liquid–vapor surface tension, σ LV , of supercooled water has been a topic of long-standing interest. In 1951, an inflection point in the temperature dependence of σ LV was reported to occur near 0 °C, but later studies, showing larger uncertainties, cast doubts on the early measurements. , Only recently, the highly accurate studies by Hrubý and co-workers became available. − Initially, in refs − , it was concluded that no anomaly occurred in σ LV ( T ) down to −26 °C ; however, the results of the latest experiment, reaching −31.4 °C, suggest that an inflection point might be possible. Theoretical studies support the existence of anomalies in liquid–vapor surface tension of supercooled water. − Using two closely related microscopic models of water-like associating fluids, Feeney and Debenedetti predicted either an inflection point or a maximum, depending on the details and assumptions of the approach.…”

The Latest Method for Surface Tension Determination: Experimental Validation

“…Since clouds contain extremely small the water drops and ice particles, the surface effects should be taken into consideration [9][10][11][12]. In the last case, research is conducted for supercooled water [13].…”