Low- and High-Density Unknown Waters at Ice-Water Interfaces

Hiromasa Niinomi, Akira Kouch, Tetsuya Hama, Hiroki Nada, Tomoya Yamazaki, Yuki Kimura

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


Experimental confirmation of liquid polymorphs of water, high-density liquid (HDL) and low-density liquid (LDL), is desired for understanding not only the liquid state of matter but also the origin of the mysterious properties of water. However, this remains challenging because the liquid-liquid critical point of water lies in experimentally inaccessible supercooling conditions known as "no man's land". Here, we show by in situ optical microscopy that droplets and layers of low- and high-density unknown waters (LDUW and HDUW) appear macroscopically depending upon ice polymorphs at non-equilibrium interfaces between water and ices under experimentally accessible (de)pressurization conditions. These unknown waters were found to have characteristic velocities (about 20 and 100 m/s for LDUW and HDUW, respectively) different from water (about 40 m/s) and quasi-liquid layers (QLLs) (about 2 and 0.2 m/s for droplet and layer forms of QLLs, respectively). Our discoveries provide insight on liquid polymorphism of water.

Original languageEnglish
Pages (from-to)4251-4256
Number of pages6
JournalJournal of Physical Chemistry Letters
Publication statusAccepted/In press - 2022

ASJC Scopus subject areas

  • Materials Science(all)
  • Physical and Theoretical Chemistry


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