Related Experiment Video
Updated: May 11, 2026
11:03
An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
Published on: December 4, 2017
Density dependence of dynamical heterogeneity in fluid methanol
Louis Loubeyre1, Muhtar Ahart, Stephen A Gramsch
1IUT Paris Jussieu, Université Paris Diderot, 75205, Paris, France.
The Journal of Chemical Physics
|May 10, 2013
Summary
This study investigates methanol
Area of Science:
- Condensed Matter Physics
- Materials Science
- Physical Chemistry
Background:
- Understanding glass-forming liquids like methanol is crucial for materials science.
- Pressure-induced changes in molecular dynamics offer insights into glass transition phenomena.
Purpose of the Study:
- To investigate the pressure-induced evolution of relaxation processes in glass-forming methanol.
- To correlate GHz and THz relaxation dynamics with density changes.
Main Methods:
- Brillouin and Raman scattering experiments were conducted on methanol under varying pressure.
- Viscoelastic theory and the Vinet equation of state were used to analyze Brillouin data.
- Analysis of Raman data focused on the Boson peak and its relaxation time.
Main Results:
- A broad maximum in the longitudinal acoustic mode linewidth was observed around 3 GPa.
- Pressure evolution of GHz-range relaxation times was determined.
- THz-range relaxation dynamics, including the Boson peak, were analyzed under pressure.
Conclusions:
- The study successfully mapped relaxation processes in methanol across GHz and THz ranges under varying pressure.
- These findings extend previous low-frequency dielectric measurements, providing a comprehensive view of methanol's dynamics.
- The research offers valuable data on the density dependence of relaxation in glass-forming systems.
More Related Videos
Related Concept Videos
02:34Comparing Intermolecular Forces: Melting Point, Boiling Point, and Miscibility
Intermolecular forces are attractive forces that exist between molecules. They dictate several bulk properties, such as melting points, boiling points, and solubilities (miscibilities) of substances. Molar mass, molecular shape, and polarity affect the strength of different intermolecular forces, which influence the magnitude of physical properties across a family of molecules.
Temporary attractive forces like dispersion are present in all molecules, whether they are polar or nonpolar. They...
Temporary attractive forces like dispersion are present in all molecules, whether they are polar or nonpolar. They...
02:56Intermolecular Forces and Physical Properties
02:57Surface Tension, Capillary Action, and Viscosity
Surface Tension
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive forces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half as many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids contract to form a shape that minimizes the number...
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive forces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half as many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids contract to form a shape that minimizes the number...
02:20Dynamic Equilibrium
A reversible chemical reaction represents a chemical process that proceeds in both forward (left to right) and reverse (right to left) directions. When the rates of the forward and reverse reactions are equal, the concentrations of the reactant and product species remain constant over time and the system is at equilibrium. A special double arrow is used to emphasize the reversible nature of the reaction. The relative concentrations of reactants and products in equilibrium systems vary greatly;...
02:05Entropy and Solvation
The process of surrounding a solute with solvent is called solvation. It involves evenly distributing the solute within the solvent. The rule of thumb for determining a solvent for a given compound is that like dissolves like. A good solvent has molecular characteristics similar to those of the compound to be dissolved. For example, polar solutions dissolve polar solutes, and apolar solvents dissolve apolar solutes. A polar solvent is a solvent that has a high dielectric constant (ϵ ≥ 15); an...
01:10¹H NMR of Labile Protons: Temporal Resolution
Protons bonded to heteroatoms such as nitrogen and oxygen exhibit a range of chemical shift values. This is due to the varying degree of hydrogen bonding between the proton and the heteroatom in other molecules. The extent of hydrogen bonding affects the electron density around the proton, thereby giving different chemical shift values for the protons in the proton NMR spectrum.
The –OH proton in alcohols typically appears in the range of δ 2 to 5 ppm but can vary depending on the specific...
The –OH proton in alcohols typically appears in the range of δ 2 to 5 ppm but can vary depending on the specific...