Inelastic neutron scattering study on boson peaks of imidazolium-based ionic liquids
Low energy excitations of 1-alkyl-3-methylimidazolium ionic liquids (ILs) have been investigated by means of neutron spectroscopy. In the spectra of inelastic scattering, a broad excitation peak referred to as a “boson peak” appeared at 1–3 meV in all of the ILs measured. The intensity of the boson peak was enhanced at the Q positions corresponding to the diffraction peaks, reflecting the in-phase vibrational nature of the boson peak. Furthermore the boson peak energy (E BP) was insensitive to the length of the alkyl-chain but changed depending on the radius of the anion. From the correlation among E BP, the anion radius, and the glass transition temperature T g, we conclude that both E BP and T g in ILs are predominantly governed by the inter-ionic Coulomb interaction which is less influenced by the alkyl-chain length. Furthermore, we also found that the E BP is proportional to the inverse square root of the molecular weight as observed in molecular glasses.
- Authors:
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[1]
; [1]
; [2]
; [2]
; [1]
; [1]
- Univ. of Tokyo, Chiba (Japan)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Publication Date:
- Grant/Contract Number:
- AC05-00OR22725
- Type:
- Accepted Manuscript
- Journal Name:
- Journal of Molecular Liquids
- Additional Journal Information:
- Journal Volume: 210; Journal Issue: 1; Journal ID: ISSN 0167-7322
- Publisher:
- Elsevier
- Research Org:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Org:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 74 ATOMIC AND MOLECULAR PHYSICS; ionic liquid; inelastic neutron scattering; boson peak; glass
- OSTI Identifier:
- 1214030
- Alternate Identifier(s):
- OSTI ID: 1250296
- Free Publicly Accessible Full Text
- Accepted Manuscript (Publisher)
-
Accepted Manuscript (DOE)
- Publisher's Version of Record
- https://doi.org/10.1016/j.molliq.2015.07.021