Characterisation of the Boson Peak from the Glass into the Liquid

28 May 2021, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

Phenomena ranging from vitrification to crystal nucleation are governed by locally ordered structures, in otherwise disordered phases, that can either inhibit or favour the growth of macroscopic order. However, such structures are ephemeral, do not typically have distinct spectral features, and are therefore critically important but largely unobservable by current methods. Illuminating these structures therefore presents the single greatest challenge in physical chemistry. The boson peak is characteristic of glasses and represents the locally ordered structures inhibiting crystallisation but is typically obscured by other spectral contributions. Here we show that depolarised Raman scattering—obtained using femtosecond optical Kerr-effect spectroscopy—in liquids consisting of highly symmetric molecules can be used to isolate the boson peak thereby allowing detailed characterisation of the intermolecular potential-energy landscape for the first time.

Keywords

Vitrification
glass transition physics
supercooling
Boson Peak
Raman scattering
Ultrafast spectroscopy
Optical Kerr Effect Spectroscopy
Terahertz spectroscopy
Toluene
Titanium alkoxides
titanium butoxide
titanium tetra-2-ethylhexyloxide
Quantum chemistry

Supplementary materials

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Title
Boson peak - SI
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