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A stochastic simulation of nonisothermal nucleation
1Nuclear Department, DCMT, HMS Sultan, Military Road, Gosport PO12 3BY, United Kingdom. barrettjc@aol.com
The Journal of Chemical Physics
|May 2, 2008
Summary
Stochastic simulations reveal nonisothermal nucleation rates in vapor are significantly lower than isothermal rates, typically 1-5%. This finding impacts understanding of cluster formation dynamics.
Area of Science:
- Physical Chemistry
- Materials Science
- Thermodynamics
Background:
- Cluster formation in supersaturated vapor is crucial for aerosol science and materials synthesis.
- Understanding nucleation rates is key to predicting phase transitions and material properties.
- Previous analytical models often simplify the complex dynamics of cluster growth and evaporation.
Purpose of the Study:
- To investigate the dynamics of small cluster growth and evaporation in vapor using stochastic simulations.
- To determine the nonisothermal nucleation rate and compare it with existing analytical models.
- To quantify the fraction of clusters that reach a critical size from a supersaturated vapor.
Main Methods:
- Stochastic simulations of cluster growth and evaporation incorporating energy-dependent rates.
- Calculation of monomer-cluster collision and decay rates using detailed balance.
- Utilizing capillarity approximation and equilibrium vapor pressure for cluster size and energy distribution.
- Simulating two-dimensional random walks in size and energy space.
Main Results:
- Simulated nucleation rates show good agreement with previously published analytical results.
- Nonisothermal nucleation rates were found to be 1% to 5% of isothermal rates in the absence of carrier gas.
- The fraction of clusters reaching a maximum size was determined from simulations.
Conclusions:
- Stochastic simulations provide a robust method for studying nucleation dynamics.
- Nonisothermal nucleation is a less efficient pathway compared to isothermal nucleation under studied conditions.
- The findings offer insights into the kinetics of phase transitions in vapor systems.
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