Gonzalez Jimenez, M. et al. (2023) Understanding the emergence of the boson peak in molecular glasses. Nature Communications, 14, 215. (doi: 10.1038/s41467-023-35878-6) (PMID:36639380) (PMCID:PMC9839737)
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Abstract
A common feature of glasses is the “boson peak”, observed as an excess in the heat capacity over the crystal or as an additional peak in the terahertz vibrational spectrum. The microscopic origins of this peak are not well understood; the emergence of locally ordered structures has been put forward as a possible candidate. Here, we show that depolarised Raman scattering in liquids consisting of highly symmetric molecules can be used to isolate the boson peak, allowing its detailed observation from the liquid into the glass. The boson peak in the vibrational spectrum matches the excess heat capacity. As the boson peak intensifies on cooling, wide-angle x-ray scattering shows the simultaneous appearance of a pre-peak due to molecular clusters consisting of circa 20 molecules. Atomistic molecular dynamics simulations indicate that these are caused by over-coordinated molecules. These findings represent an essential step toward our understanding of the physics of vitrification.
| Item Type: | Articles |
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| Additional Information: | K.W. acknowledges funding by a grant from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 832703). K.W. and H.M.S. acknowledge funding by Leverhulme Trust Research Project Grant RPG-2018-350. We thank the Diamond Light Source for access to beamline I22 to carry out SWAXS experiments (proposal numbers SM27885 and SM28529). K.W. thanks the Engineering and Physical Sciences Research Council (EPSRC) for support through grants EP/J009733/1, EP/K034995/1, EP/N508792/1, and EP/N007417/1. G.M. acknowledges financial support from the Slovenian Research Agency (research core funding No. P1-0021). T.B. thanks the EPSRC for a studentship through the Centre for Doctoral Training in Mathematics for Real-World Systems II (EP/S022244/1). T.B. and G.C.S. also gratefully acknowledge the use of SULIS, which was funded by the EPSRC (EP/T022108/1), via the HPC Midlands+ Consortium. |
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | Russell, Dr Ben and Senn, Dr Hans and Gonzalez Jimenez, Dr Mario and Tukachev, Mr Nikita and Wynne, Professor Klaas and Farrell, Mr Andrew |
| Authors: | Gonzalez Jimenez, M., Barnard, T., Russell, B. A., Tukachev, N. V., Javornik, U., Hayes, L.-A., Farrell, A. J., Guinane, S., Senn, H. M., Smith, A. J., Wilding, M., Mali, G., Nakano, M., Miyazaki, Y., McMillan, P., Sosso, G. C., and Wynne, K. |
| College/School: | College of Science and Engineering > School of Chemistry |
| Journal Name: | Nature Communications |
| Publisher: | Nature Research |
| ISSN: | 2041-1723 |
| ISSN (Online): | 2041-1723 |
| Copyright Holders: | Copyright © 2023 The Authors |
| First Published: | First published in Nature Communications 14: 215 |
| Publisher Policy: | Reproduced under a Creative Commons License |
| Related URLs: | |
| Data DOI: | 10.5525/gla.researchdata.1381 |
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