Publication
Article Metrics
Citations
Online attention
Pressure and temperature dependence of local structure and dynamics in an ionic liquid
Authors:
Filippa
Lundin
(Chalmers University of Technology)
,
Henriette Wase
Hansen
(Chalmers University of Technology; Roskilde University; Institut Laue-Langevin)
,
Karolina
Adrjanowicz
(University of Silesia)
,
Bernhard
Frick
(Institut Laue-Langevin)
,
Daniel
Rauber
(Saarland University)
,
Rolf
Hempelmann
(Saarland University)
,
Olga
Shebanova
(Diamond Light Source)
,
Kristine
Niss
(Roskilde University)
,
Aleksandar
Matic
(Chalmers University of Technology)
Co-authored by industrial partner:
No
Type:
Journal Paper
Journal:
The Journal Of Physical Chemistry B
State:
Published (Approved)
Published:
March 2021
Diamond Proposal Number(s):
20249
Abstract: A detailed understanding of the local dynamics in ionic liquids remains an important aspect in the design of new ionic liquids as advanced functional fluids. Here, we use small-angle X-ray scattering and quasi-elastic neutron spectroscopy to investigate the local structure and dynamics in a model ionic liquid as a function of temperature and pressure, with a particular focus on state points (P,T) where the macroscopic dynamics, i.e., conductivity, is the same. Our results suggest that the initial step of ion transport is a confined diffusion process, on the nanosecond timescale, where the motion is restricted by a cage of nearest neighbors. This process is invariant considering timescale, geometry, and the participation ratio, at state points of constant conductivity, i.e., state points of isoconductivity. The connection to the nearest-neighbor structure is underlined by the invariance of the peak in the structure factor corresponding to nearest-neighbor correlations. At shorter timescales, picoseconds, two localized relaxation processes of the cation can be observed, which are not directly linked to ion transport. However, these processes also show invariance at isoconductivity. This points to that the overall energy landscape in ionic liquids responds in the same way to density changes and is mainly governed by the nearest-neighbor interactions.
Journal Keywords: Salts; Diffusion; Chemical structure; Solvents; Cations
Subject Areas:
Chemistry
Instruments:
I22-Small angle scattering & Diffraction
Added On:
08/03/2021 08:34
Discipline Tags:
Physical Chemistry
Chemistry
Technical Tags:
Scattering
Small Angle X-ray Scattering (SAXS)