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Surface entropy of rare-gas clusters
S Prasalovich1, K Hansen, M Kjellberg
1Department of Physics, Gothenburg University, SE-41296 Gothenburg, Sweden.
The Journal of Chemical Physics
|September 17, 2005
Summary
We studied argon and xenon clusters to determine their dissociation energies. Results show differences from theoretical models, suggesting surface atom entropy plays a key role in cluster stability.
Area of Science:
- Physical Chemistry
- Materials Science
- Computational Chemistry
Background:
- Understanding cluster stability is crucial for materials science.
- Lennard-Jones potentials are commonly used to model atomic interactions in clusters.
- Experimental data on cluster dissociation energies can validate theoretical models.
Purpose of the Study:
- To experimentally determine the relative dissociation energies of argon (ArN+) and xenon (XeN+) clusters.
- To compare experimental findings with theoretical predictions based on ground-state energies.
- To investigate the influence of entropic effects on cluster stability.
Main Methods:
- Producing ArN+ and XeN+ clusters using a supersonic expansion source.
- Inverting abundance data to calculate relative dissociation energies.
- Analyzing deviations from theoretical Lennard-Jones cluster models.
Main Results:
- Measured relative dissociation energies for ArN+ and XeN+ clusters.
- Observed discrepancies between experimental and theoretical values, particularly near shell and subshell closings (N=55, 71, 147).
- Identified conformational entropy of surface atoms and vacancies as a significant factor explaining these differences.
Conclusions:
- Experimental dissociation energies of ArN+ and XeN+ clusters deviate from simple ground-state energy models.
- Conformational entropy significantly impacts the stability of atomic clusters.
- This study highlights the importance of including entropic contributions in theoretical cluster models.