Understanding the glass transition requires getting the picture of the dynamical processes that intervene in it. Glass-forming liquids show a characteristic decoupling of relaxation processes when they are cooled down towards the glassy state. The faster (beta(JG)) process is still under scrutiny, and its full explanation necessitates information at the microscopic scale. To this aim, nuclear gamma-resonance time-domain interferometry (TDI) has been utilized to investigate 5-methyl-2-hexanol, a hydroge-nbonded liquid with a pronounced beta(JG) process as measured by dielectric spectroscopy. TDI probes in fact the center-of-mass, molecular dynamics at scattering-vectors corresponding to both inter- and intra-molecular distances. Our measurements demonstrate that, in the undercooled liquid phase, the beta(JG) relaxation can be visualized as a spatially-restricted rearrangement of molecules within the cage of their closest neighbours accompanied by larger excursions which reach out at least the inter-molecular scale and are related to cage-breaking events. In-cage rattling and cage-breaking processes therefore coexist in the beta(JG) relaxation.

A microscopic look at the Johari-Goldstein relaxation in a hydrogen-bonded glass-former / Caporaletti, F.; Capaccioli, S.; Valenti, S.; Mikolasek, M.; Chumakov, A. I.; Monaco, G.. - In: SCIENTIFIC REPORTS. - ISSN 2045-2322. - 9:1(2019), p. 14319. [10.1038/s41598-019-50824-7]

A microscopic look at the Johari-Goldstein relaxation in a hydrogen-bonded glass-former

Caporaletti F.;Monaco G.
2019-01-01

Abstract

Understanding the glass transition requires getting the picture of the dynamical processes that intervene in it. Glass-forming liquids show a characteristic decoupling of relaxation processes when they are cooled down towards the glassy state. The faster (beta(JG)) process is still under scrutiny, and its full explanation necessitates information at the microscopic scale. To this aim, nuclear gamma-resonance time-domain interferometry (TDI) has been utilized to investigate 5-methyl-2-hexanol, a hydroge-nbonded liquid with a pronounced beta(JG) process as measured by dielectric spectroscopy. TDI probes in fact the center-of-mass, molecular dynamics at scattering-vectors corresponding to both inter- and intra-molecular distances. Our measurements demonstrate that, in the undercooled liquid phase, the beta(JG) relaxation can be visualized as a spatially-restricted rearrangement of molecules within the cage of their closest neighbours accompanied by larger excursions which reach out at least the inter-molecular scale and are related to cage-breaking events. In-cage rattling and cage-breaking processes therefore coexist in the beta(JG) relaxation.
2019
1
Caporaletti, F.; Capaccioli, S.; Valenti, S.; Mikolasek, M.; Chumakov, A. I.; Monaco, G.
A microscopic look at the Johari-Goldstein relaxation in a hydrogen-bonded glass-former / Caporaletti, F.; Capaccioli, S.; Valenti, S.; Mikolasek, M.; Chumakov, A. I.; Monaco, G.. - In: SCIENTIFIC REPORTS. - ISSN 2045-2322. - 9:1(2019), p. 14319. [10.1038/s41598-019-50824-7]
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11572/243656
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? 9
  • Scopus 24
  • ???jsp.display-item.citation.isi??? 23
social impact