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Updated: Jun 29, 2026
11:32
High Pressure Single Crystal Diffraction at PX^2
Published on: January 16, 2017
High-pressure effects in pyrene crystals: vibrational spectroscopy
1Institute for Shock Physics and Department of Physics, Washington State University, Pullman, Washington 99164-2816, USA.
The Journal of Physical Chemistry. A
|October 2, 2008
Summary
High pressure transforms pyrene crystals into new phases, eventually leading to irreversible chemical changes and the formation of amorphous hydrogenated carbon (a-C:H) under extreme conditions.
Area of Science:
- Materials Science
- Solid-state Chemistry
- Spectroscopy
Background:
- Pyrene is a polycyclic aromatic hydrocarbon with potential applications in materials science.
- Understanding its behavior under high pressure is crucial for exploring novel material properties and synthesis routes.
Purpose of the Study:
- To investigate the structural and chemical transformations of pyrene crystals under high pressure.
- To identify phase transitions and irreversible chemical changes using spectroscopic techniques.
Main Methods:
- Raman spectroscopy was employed to analyze external and internal vibrational modes up to 11 GPa.
- Fourier-transform infrared (FTIR) spectroscopy was used to characterize the recovered pyrene structure after high-pressure treatment.
- High pressure was applied to pyrene crystals to induce phase transitions and chemical modifications.
Main Results:
- A phase transition from pyrene I to pyrene III was observed around 0.3 GPa.
- Further pressure increase (above 2.0 GPa) led to the formation of a new phase, evidenced by broadened internal modes and increased fluorescence.
- Compression to 40 GPa resulted in irreversible chemical changes, forming an amorphous hydrogenated carbon (a-C:H) structure.
Conclusions:
- Pyrene undergoes distinct phase transitions under high pressure, altering its crystalline structure.
- Extreme pressure induces irreversible chemical modifications, transforming pyrene into amorphous hydrogenated carbon.
- Spectroscopic methods are effective in characterizing high-pressure-induced transformations in molecular crystals.
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