Correlation between macroscopic and microscopic relaxation dynamics of water: Evidence for two liquid forms

Area of Science:

• Physical Chemistry
• Biophysics

Background:

• Water's unique properties are crucial for life, stemming from its hydrogen-bonding network and molecular dynamics.
• Investigating water dynamics is challenging due to its strong absorption of terahertz radiation.

Purpose of the Study:

• To characterize the terahertz dielectric response of water across a wide temperature range.
• To explore the molecular motions and relaxation processes in water.
• To investigate the potential existence of distinct liquid forms of water.

Main Methods:

• Utilized a high-precision terahertz spectrometer to measure water's dielectric response.
• Covered a temperature range from supercooled liquid to near the boiling point.

Main Results:

• Identified dynamic relaxation processes including collective orientation, single-molecule rotation, and hydrogen bond rearrangements.
• Established a direct correlation between macroscopic and microscopic relaxation dynamics.
• Provided evidence for two distinct liquid forms of water with differing transition temperatures and activation energies.

Conclusions:

• The study offers a direct method to test microscopic computational models of water dynamics.
• Findings enhance our understanding of water's complex behavior and its implications for life.