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Intermediate phases during solid to liquid transitions in long-chain n-alkanes.
Stella Corsetti1, Thomas Rabl2, David McGloin1
1SUPA, School of Science & Engineering, University of Dundee, Nethergate, Dundee, DD1 4HN, Scotland, UK. s.corsetti@dundee.ac.uk.
Physical Chemistry Chemical Physics : PCCP
|May 18, 2017
Summary
Raman spectroscopy reveals differences in melting speeds and crystal structures for n-alkanes. Hexadecane melts almost instantly, while pentadecane exhibits a rotator phase, unlike tetradecane.
Area of Science:
- Physical Chemistry
- Materials Science
- Spectroscopy
Background:
- n-alkanes are crucial in various industries, including cosmetics and automotive.
- Understanding their solid-to-liquid phase transitions is vital for material applications.
Purpose of the Study:
- To investigate the solid-to-liquid phase transition of tetradecane, pentadecane, and hexadecane.
- To determine the temperature, speed, and structural changes during melting using Raman spectroscopy.
Main Methods:
- Temperature-dependent Raman spectroscopy was performed on tetradecane, pentadecane, and hexadecane.
- Analysis included frequency shifts, band widths, intensity ratios, and principal component analysis.
Main Results:
- Hexadecane exhibited an almost instantaneous solid-to-liquid phase transition.
- Tetradecane showed a faster transition than pentadecane.
- A rotator phase was identified in pentadecane, and crystalline structures were assigned (triclinic for tetradecane/hexadecane, orthorhombic for pentadecane).
Conclusions:
- The melting dynamics and crystalline structures of n-alkanes vary significantly with chain length.
- Raman spectroscopy is effective in characterizing phase transitions and solid-state structures of hydrocarbons.
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