Related Experiment Video
Updated: May 7, 2026
11:03
An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
Published on: December 4, 2017
Particle dynamics in two-dimensional random-energy landscapes: experiments and simulations.
Florian Evers1, Christoph Zunke, Richard D L Hanes
1Condensed Matter Physics Laboratory, Heinrich-Heine-University, Universitätsstraße 1, 40225 Düsseldorf, Germany.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|September 17, 2013
Summary
Investigating colloidal particle dynamics in random landscapes reveals how landscape roughness affects Brownian motion. Two-dimensional landscapes allow particles to escape traps more easily than one-dimensional ones.
Area of Science:
- Soft Matter Physics
- Statistical Mechanics
Background:
- Understanding particle dynamics in disordered systems is crucial for materials science and biophysics.
- Brownian dynamics in random potential energy landscapes presents complex behavior influenced by disorder.
Purpose of the Study:
- To experimentally and computationally investigate colloidal particle dynamics in two-dimensional random potential energy landscapes.
- To analyze the effect of landscape roughness, controlled by Gaussian distribution width, on particle motion.
Main Methods:
- Optical generation of 2D energy landscapes using holographic setups and spatial light modulators.
- Tracking colloidal particle trajectories via video microscopy.
- Monte Carlo simulations of Brownian dynamics.
- Characterization using time-dependent diffusion coefficient, mean squared displacement, van Hove function, and non-Gaussian parameter.
Main Results:
- Particle dynamics exhibit initial diffusion, followed by a subdiffusive regime, and eventual recovery of diffusion.
- The long-time diffusion coefficient's dependence on landscape roughness aligns with theoretical predictions.
- Compared to 1D, 2D landscapes show weaker intermediate-time localization and faster recovery of diffusion due to trap avoidance.
Conclusions:
- The study elucidates the impact of disorder and dimensionality on colloidal particle dynamics.
- Experimental and simulation results confirm theoretical predictions for diffusion in random landscapes.
- The 2D nature of the landscape facilitates particle escape from local potential minima, influencing overall dynamics.
More Related Videos
Related Concept Videos
01:18First Law: Particles in Two-dimensional Equilibrium
Recall that a particle in equilibrium is one for which the external forces are balanced. Static equilibrium involves objects at rest, and dynamic equilibrium involves objects in motion without acceleration; but it is important to remember that these conditions are relative. For instance, an object may be at rest when viewed from one frame of reference, but that same object would appear to be in motion when viewed by someone moving at a constant velocity.
Newton's first law tells us about the...
Newton's first law tells us about the...
01:24The Kinetic Model of Gases
The kinetic model of gases explains the properties of a perfect gas using three main assumptions: molecules move in ceaseless random motion, their size is negligible compared to the distances between them, and they do not interact except during perfectly elastic collisions. The total energy of a gas is the sum of the kinetic energies of all its constituent molecules. The pressure exerted by the gas arises from the continual bombardment of the container walls by billions of colliding molecules.
01:05Collisions in Multiple Dimensions: Introduction
It is far more common for collisions to occur in two dimensions; that is, the initial velocity vectors are neither parallel nor antiparallel to each other. Let's see what complications arise from this. The first idea is that momentum is a vector. Like all vectors, it can be expressed as a sum of perpendicular components (usually, though not always, an x-component and a y-component, and a z-component if necessary). Thus, when the statement of conservation of momentum is written for a problem,...
01:10First Law: Particles in One-dimensional Equilibrium
Newton's first law of motion states that a body at rest remains at rest, or if in motion, remains in motion at constant velocity, unless acted on by a net external force. It also states that there must be a cause for any change in velocity (a change in either magnitude or direction) to occur. This cause is a net external force. For example, consider what happens to an object sliding along a rough horizontal surface. The object quickly grinds to a halt, due to the net force of friction. If we...
02:32The de Broglie Wavelength
In the macroscopic world, objects that are large enough to be seen by the naked eye follow the rules of classical physics. A billiard ball moving on a table will behave like a particle; it will continue traveling in a straight line unless it collides with another ball, or it is acted on by some other force, such as friction. The ball has a well-defined position and velocity or well-defined momentum, p = mv, which is defined by mass m and velocity v at any given moment. This is the typical...
01:21Molecular Kinetic Energy
The word "gas" comes from the Flemish word meaning "chaos," first used to describe vapors by the chemist J. B. van Helmont. Consider a container filled with gas, with a continuous and random motion of molecules. During collisions, the velocity component parallel to the wall is unchanged, and the component perpendicular to the wall reverses direction but does not change in magnitude. If the molecule’s velocity changes in the x-direction, then its momentum is changed. During the short time of the...