The hydrogen-bond collective dynamics in liquid methanol

Area of Science:

• Physical Chemistry
• Materials Science
• Chemical Physics

Background:

• Hydrogen-bonded (HB) systems exhibit complex thermodynamic and microscopic behaviors despite simple molecular structures.
• The dynamics of molecules within HB systems remain incompletely understood despite extensive research.

Purpose of the Study:

• To investigate the microscopic dynamics of liquid methanol, a prototypical HB alcohol.
• To compare methanol's dynamics with those of liquid water, the most studied HB system.
• To elucidate the role of HB dynamics in the THz microscopic behavior of these liquids.

Main Methods:

• Utilized neutron Brillouin scattering (NBS) for experimental probing.
• Employed molecular dynamics (MD) simulations for computational analysis.
• Performed a comparative analysis between methanol and water dynamics.

Main Results:

• Identified common THz microscopic dynamics between liquid methanol and liquid water.
• Revealed a richer dynamic behavior in methanol than previously known.
• Observed striking analogies between methanol's dynamics and those of liquid/supercooled water.
• Questioned the direct assignment of certain dynamical properties to the tetrahedral structure of water based on differing structural properties.

Conclusions:

• Hydrogen bond dynamics significantly influence the THz microscopic behavior of both methanol and water.
• Methanol exhibits complex dynamics analogous to water, challenging previous assumptions.
• The study highlights similarities in characteristic decay times and hydrogen bond lifetimes, emphasizing the universal role of HB dynamics.