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Vibrational Properties of p-Terphenyl
Kai Zhang1,2,3, Ren-Shu Wang3, Xiao-Jia Chen3
1Key Laboratory of Materials Physics, Institute of Solid State Physics , Chinese Academy of Sciences , Hefei 230031 , China.
The Journal of Physical Chemistry. A
|August 2, 2018
Summary
Raman spectroscopy reveals anomalous vibrational properties in p-terphenyl near 193 K. This behavior stems from reduced anharmonic coupling as the crystal enters an ordered state, impacting frequencies, widths, and intensities.
Area of Science:
- Solid State Physics
- Materials Science
- Spectroscopy
Background:
- Pristine p-terphenyl is a molecular crystal with complex vibrational properties.
- Understanding temperature-dependent vibrational behavior is crucial for materials characterization.
- Anharmonic coupling significantly influences molecular crystal dynamics.
Purpose of the Study:
- To investigate the low-temperature vibrational properties of pristine p-terphenyl.
- To analyze the impact of temperature-induced phase transitions on vibrational modes.
- To elucidate the role of anharmonicity in observed spectral anomalies.
Main Methods:
- Detailed Raman spectroscopy analysis at low temperatures.
- Observation and characterization of vibrational mode anomalies.
- Correlation of spectral changes with crystalline state transitions.
Main Results:
- Nearly all vibrational modes showed anomalous changes in frequency, width, and intensity around 193 K.
- Spectrum weight drops led to peak splitting, including lattice and intramolecular modes.
- Reduced vibrational anharmonic coupling in the ordered state was identified as the cause.
Conclusions:
- The study highlights significant anomalies in p-terphenyl's vibrational properties below 193 K.
- Decreased anharmonic coupling in the ordered crystalline state drives these spectral changes.
- Findings provide critical insights into the internal vibrational dynamics of p-terphenyl.
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