Anomalous anti-Stokes Raman scattering during epoxy-amine polymerization
In thermal equilibrium the Stokes Raman scatter should always be greater than the anti-Stokes; however, in some rare cases anomalous anti-Stokes Raman scattering (AASR) has been observed. This work presents the first observations of AASR during epoxy-amine polymerization and demonstrates the potenti...
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| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2025-10-01
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| Series: | Polymer Testing |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S0142941825002570 |
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| Summary: | In thermal equilibrium the Stokes Raman scatter should always be greater than the anti-Stokes; however, in some rare cases anomalous anti-Stokes Raman scattering (AASR) has been observed. This work presents the first observations of AASR during epoxy-amine polymerization and demonstrates the potential to utilize this phenomenon as a means of noncontact heat flow measurement. Even though the phonon population is unbounded, experimental evidence shows that the AASR can be phenomenologically explained from an entropic perspective as negative-absolute-temperature-like behavior. Furthermore, since polymerization is a non-equilibrium thermodynamic process, a statistical physics-based heat flow kinetics model was developed which simultaneously describes the observed AASR and allows for the extraction of the excess phonon population. This excess phonon population was combined with a simplified Debye model for the phonon density of states to calculate an effective heat flow, which closely corresponds to the heat flow measured by isothermal differential scanning calorimetry. |
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| ISSN: | 1873-2348 |