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Universal behavior of nonequilibrium fluctuations in free diffusion processes
1Dipartimento di Fisica and Istituto Nazionale per la Fisica della Materia, Universita di Milano, via Celoria 16, 20133 Milano, Italy.
Summary
Giant nonequilibrium fluctuations are a universal feature of free diffusion in liquid mixtures and macromolecular solutions. These fluctuations were observed and characterized using a quantitative shadowgraph technique, revealing a universal scaling behavior.
Area of Science:
- Physical Chemistry
- Soft Matter Physics
- Fluid Dynamics
Background:
- Free diffusion is a fundamental process in liquid mixtures and solutions.
- Understanding fluctuations is crucial for characterizing dynamic processes.
- Previous studies have not fully explored nonequilibrium fluctuations during diffusion.
Purpose of the Study:
- To investigate the presence and nature of giant nonequilibrium fluctuations during free diffusion.
- To quantify these fluctuations using a precise measurement technique.
- To establish the universality of these fluctuations in different diffusive systems.
Main Methods:
- Utilizing a quantitative shadowgraph technique to measure the static structure factor of fluctuations.
- Analyzing data from ordinary liquid mixtures and macromolecular solutions.
- Applying data rescaling methods to compare structure factors across different times and samples.
Main Results:
- Demonstrated the existence of giant nonequilibrium fluctuations during free diffusion.
- Successfully measured the static structure factor of these fluctuations.
- Showed that structure factors from various conditions rescale onto a single master curve without adjustable parameters.
Conclusions:
- Giant nonequilibrium fluctuations are a universal characteristic of free diffusion processes.
- The observed universal scaling provides strong evidence for this universality.
- This finding offers new insights into the dynamics of liquid mixtures and macromolecular solutions.