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Concentration fluctuations in non-isothermal reaction-diffusion systems. II. The nonlinear case
D Bedeaux1, J M Ortiz de Zárate, I Pagonabarraga
1Department of Chemistry, Norwegian University of Science and Technology, Trondheim 7491, Norway. dick.bedeaux@chem.ntnu.no
The Journal of Chemical Physics
|October 7, 2011
Summary
Non-equilibrium temperature gradients enhance concentration fluctuations in binary fluid mixtures. These fluctuations are long-ranged, offering experimental ways to distinguish reaction control mechanisms.
Area of Science:
- Chemical Physics
- Thermodynamics
- Fluid Dynamics
Background:
- Studies fluctuations in non-isothermal reaction-diffusion systems.
- Extends previous work on near-equilibrium systems.
- Focuses on binary fluid mixtures with association-dissociation reactions.
Purpose of the Study:
- Analyze hydrodynamic fluctuations in a driven reaction-diffusion system.
- Investigate the impact of temperature gradients on concentration fluctuations.
- Develop a theoretical framework using mesoscopic non-equilibrium thermodynamics.
Main Methods:
- Applied mesoscopic non-equilibrium thermodynamics.
- Derived the law of mass action and fluctuation-dissipation theorems.
- Analyzed the wave number dependence of fluctuation intensity.
Main Results:
- Observed enhanced intensity of concentration fluctuations due to temperature gradients.
- Found that non-equilibrium fluctuations are spatially long-ranged.
- Identified a crossover in fluctuation intensity (q^-4 to q^-2) related to wavelength and penetration depth.
Conclusions:
- Non-equilibrium fluctuations in non-isothermal reaction-diffusion systems are consistently long-ranged.
- The observed crossover provides a method to experimentally differentiate diffusion- versus activation-controlled reaction regimes.
- This research deepens the understanding of fluctuations in complex chemical systems driven far from equilibrium.
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