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Inverse condensation of adsorbed molecules with two conformations.
Joël A K L Picard1, Thomas Speck2
1Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7-9, 55128 Mainz, Germany.
The Journal of Chemical Physics
|January 21, 2023
Summary
Heating can cause adsorbed organic molecules to condense, defying conventional phase transition intuition. This inverse condensation phenomenon was studied using a lattice model and simulations.
Area of Science:
- Surface science
- Physical chemistry
- Condensed matter physics
Background:
- Conventional gas-liquid phase transitions exhibit monotonic positive slopes, where cooling leads to condensation.
- Recent experiments show adsorbed organic molecules partially dissolving and mobilizing upon cooling.
Purpose of the Study:
- To investigate the inverse phenomenon of adsorbed organic molecule condensation upon heating.
- To model and understand the behavior of molecules with distinct conformations.
Main Methods:
- Development of a three-state lattice model (unoccupied, two molecular conformations).
- Application of Monte Carlo simulations and mean-field theory.
- Analytical solution using the 2D Ising model.
Main Results:
- Demonstration of condensation occurring upon heating, contrary to typical phase transitions.
- Identification of conditions for inverse condensation based on molecular conformations and their properties.
Conclusions:
- The study presents a model for inverse condensation driven by heating.
- Findings are applicable to molecules with differing entropies or heat capacities, offering insights into surface-confined phase behavior.
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