Related Experiment Video
Updated: Jun 8, 2026
11:03
An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
Published on: December 4, 2017
Low-frequency vibrations of soft colloidal glasses.
Ke Chen1, Wouter G Ellenbroek, Zexin Zhang
1Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Physical Review Letters
|September 28, 2010
Summary
Experiments on tunable hydrogel particle packings reveal vibrational properties similar to jamming and glasses. Compression above the jamming transition shifts the boson peak to higher frequencies.
Area of Science:
- Soft matter physics
- Materials science
- Statistical mechanics
Background:
- Colloidal particles and hydrogels are widely studied in soft matter.
- Jamming transition is a key phenomenon in disordered systems.
- Vibrational properties are crucial for understanding material behavior.
Purpose of the Study:
- To investigate the vibrational properties of two-dimensional colloidal particle packings.
- To tune the packing fraction using temperature-dependent hydrogel particles.
- To explore the relationship between jamming and vibrational spectra.
Main Methods:
- Experimental manipulation of two-dimensional colloidal thermosensitive hydrogel particle packings.
- Tuning particle packing fraction by temperature variation above the jamming transition.
- Measuring particle displacement correlations to extract vibrational properties of an undamped 'shadow' system.
Main Results:
- Extracted vibrational properties are analogous to zero-temperature sphere packings.
- Observed similarities to vibrational spectra in atomic and molecular glasses.
- Identified a boson peak in the low-frequency vibrational spectrum.
- Demonstrated that the boson peak shifts to higher frequencies with increased compression above jamming.
Conclusions:
- The vibrational properties of tunable jammed hydrogel systems resemble those of idealized jammed sphere packings and amorphous solids.
- Temperature-controlled compression provides a method to study jamming phenomena and their impact on vibrational dynamics.
- The observed boson peak and its frequency shift offer insights into the fundamental nature of jamming and disordered materials.
Related Concept Videos
03:22Colloids
Children at play often make suspensions such as mixtures of mud and water, flour and water, or a suspension of solid pigments in water known as tempera paint. These suspensions are heterogeneous mixtures composed of relatively large particles that are visible to the naked eye or can be seen with a magnifying glass. They are cloudy, and the suspended particles settle out after mixing. On the other hand, a solution is a homogeneous mixture in which no settling occurs and in which the dissolved...
01:29The Colloidal State
The formation of a colloidal system is exemplified by an aqueous solution containing Cl− ions is introduced to another containing Ag+ ions, resulting in the precipitation of solid AgCl as extremely tiny crystals. Instead of settling out as a filterable precipitate, these crystals remain suspended in the liquid, showcasing a colloidal system.A colloidal system involves colloidal particles within the approximate range of 1 to 1000 nm in at least one dimension, dispersed in a medium called the...
01:17Colloids and Suspensions
Children at play often make suspensions such as mixtures of mud and water, flour and water, or a suspension of solid pigments in water known as tempera paint. These suspensions are heterogeneous mixtures composed of relatively large particles visible to the naked eye or seen with a magnifying glass. They are cloudy, and the suspended particles settle out after mixing. The suspended particles in a suspension settle out after some time of mixing. The separation of particles from a suspension is...
01:09Colloidal precipitates
The high insolubility of some precipitates can result in an unfavorable relative supersaturation. This can lead to colloidal particles with a large surface-to-mass ratio, where adsorption is promoted. For instance, in the precipitation of silver chloride, silver ions are adsorbed on the surface of the colloidal particles, forming a primary layer. This layer attracts ions of opposite charge (such as nitrate ions), forming a diffuse secondary layer of adsorbed ions. This electric double layer...
01:01Sound Waves
Sound waves can be thought of as fluctuations in the pressure of a medium through which they propagate. Since the pressure also makes the medium's particles vibrate along its direction of motion, the waves can be modeled as the displacement of the medium's particles from their mean position.
Sound waves are longitudinal in most fluids because fluids cannot sustain any lateral pressure. In solids, however, shear forces help in propagating the disturbance in the lateral direction as well. Hence,...
Sound waves are longitudinal in most fluids because fluids cannot sustain any lateral pressure. In solids, however, shear forces help in propagating the disturbance in the lateral direction as well. Hence,...
01:28Standing Waves in a Cavity
A household microwave and lasers are examples of standing electromagnetic waves in a cavity. When two conducting metal plates are placed parallel at the nodal planes, it creates a cavity where standing waves are formed. The cavity between the two planes is analogous to a stretched string held at the points x = 0 and x = L. Here, the distance 'L' between the two planes must be an integer multiple of half of the wavelength. The wavelengths that satisfy this condition are given by: