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URN to cite this document: urn:nbn:de:bvb:703-epub-9174-1
Title data
Rößler, Ernst ; Becher, Manuel:
Relaxation spectra of molecular glass formers probed by tandem Fabry–Perot interferometry and photon correlation spectroscopy : A critical re-assessment.
In: The Journal of Chemical Physics.
Vol. 163
(2025)
Issue 5
.
- 054510.
ISSN 1089-7690
DOI der Verlagsversion: https://doi.org/10.1063/5.0273910
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Project information
| Project title: |
Project's official title Project's id From proton to deuteron relaxometry: The next generation of field-cycling NMR relaxometers 407261664 Open Access Publizieren No information |
|---|---|
| Project financing: |
Deutsche Forschungsgemeinschaft |
Abstract
Relaxation spectra of molecular glass formers measured by tandem Fabry–Perot interferometry (TFPI) and by photon correlation spectroscopy (PCS) are revisited from well above Tm down to Tg. We scrutinize the claim that a generic relaxation stretching is found close to Tg, while varying stretching is established at high temperatures. The TFPI spectra observed in this work reveal no change of the stretching over a large temperature range, and a Cole–Davidson susceptibility yields stretching parameters within βCD = 0.39–0.80. The spectra display a high-frequency excess wing contribution, which prohibits a single power law description of the high-frequency flank of the main relaxation. Corresponding PCS decays measured close to Tg display no change in the stretching either. Yet, the PCS spectra are overall broader than the TFPI spectra. They exhibit some variation and are superiorly described by a Kohlrausch function with βK = 0.52–0.73. Three of the eight systems significantly deviate from the previously reported generic relaxation function. We do not find indications that the spectral width changes within a narrow temperature interval to bridge the different stretching monitored by the two techniques. In addition to other possible explanations, we consider a sharp transition of the dynamics in the ns range not covered by the two techniques so far. Comparing PCS spectra of weakly polar liquids with their dielectric spectra, we find counterexamples of the claim that they become identical; the PCS spectra are narrower in these cases. Still, in this limit, the dielectric spectra display identical spectral shapes.
Further data
| Item Type: | Article in a journal |
|---|---|
| DDC Subjects: | 500 Science > 530 Physics |
| Institutions of the University: | Research Institutions > Central research institutes > Nordbayerisches Zentrum für NMR-Spektroskopie - NMR-Zentrum Research Institutions Research Institutions > Central research institutes |
| Language: | English |
| Originates at UBT: | Yes |
| URN: | urn:nbn:de:bvb:703-epub-9174-1 |
| Date Deposited: | 08 May 2026 12:48 |
| Last Modified: | 08 May 2026 12:48 |
| URI: | https://epub.uni-bayreuth.de/id/eprint/9174 |
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