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Crossover from first-order to critical wetting: short-range tricritical wetting
D Ross1, D Bonn, A I Posazhennikova
1National Institute of Standards & Technology, 100 Bureau Drive, Stop 8360, Gaithersburg, Maryland 20899-8360, USA. david.ross@nist.gov
Physical Review Letters
|November 3, 2001
Summary
This study investigates liquid mixtures, revealing a transition from first-order to critical wetting as alkane chain length changes. A tricritical wetting point was identified, aligning with mean-field model predictions.
Area of Science:
- Physical Chemistry
- Surface Science
- Thermodynamics
Background:
- Wetting phenomena in liquid mixtures are crucial for understanding interfacial behavior.
- The transition between continuous (critical) and discontinuous (first-order) wetting is a key area of research.
Purpose of the Study:
- To investigate the crossover between critical and first-order wetting transitions in methanol-alkane mixtures.
- To identify the tricritical wetting point and compare experimental results with theoretical models.
Main Methods:
- Systematic variation of n-alkane chain length in methanol mixtures.
- Measurement of film thickness.
- Determination of the surface specific heat exponent.
Main Results:
- A crossover from first-order to critical wetting was observed for n-alkanes with carbon numbers between 11 (undecane) and 9 (nonane).
- A tricritical wetting point was located between effective alkane carbon numbers of 9.6 and 10.
- The specific heat exponent variation in the tricritical region showed good agreement with a short-range interaction mean-field model.
Conclusions:
- The study successfully demonstrates the crossover in wetting behavior and identifies a tricritical point in methanol-alkane mixtures.
- Experimental findings support the validity of mean-field models for describing wetting transitions with short-range interactions.