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High-Pressure Effects in Pyrene Crystals: Vibrational Spectroscopy

The response of pyrene crystals to high pressure was examined using Raman and FTIR spectroscopies. Raman spectra of external and internal modes were measured up to 11 GPa. Changes in the external modes were observed at ∼0.3 GPa, indicating the onset of a phase transition. We demonstrated that at thi...

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Bibliographic Details
Published in:The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 2008-10, Vol.112 (42), p.10546-10551
Main Authors: Sun, B, Dreger, Z. A, Gupta, Y. M
Format: Article
Language:English
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Summary:The response of pyrene crystals to high pressure was examined using Raman and FTIR spectroscopies. Raman spectra of external and internal modes were measured up to 11 GPa. Changes in the external modes were observed at ∼0.3 GPa, indicating the onset of a phase transition. We demonstrated that at this pressure pyrene I (P21/a, 4 mol/unit cell) transforms to pyrene III (P21/a, 2 mol/unit cell). Further increase of pressure produced a gradual broadening of the internal modes and an increase of fluorescence background, indicating the formation of another phase above 2.0 GPa. Irreversible chemical changes were observed upon gradual compression to 40 GPa. FTIR spectroscopy of the recovered product indicated a transformation of pyrene into an amorphous hydrogenated carbon (a-C:H) structure.
ISSN:1089-5639
1520-5215
DOI:10.1021/jp806382x