Field Cycling Nuclear Magnetic Resonance (FC NMR) relaxation studies are reported for three ionic liquids: 1-ethyl-3- methylimidazolium thiocyanate (EMIM-SCN, 220–258 K), 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM-BF4, 243–318 K), and 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6, 258–323 K). The dispersion of 1H spin-lattice relaxation rate R1(ω) is measured in the frequency range of 10 kHz–20 MHz, and the studies are complemented by 19F spin-lattice relaxation measurements on BMIM-PF6 in the corresponding frequency range. From the 1H relaxation results self-diffusion coefficients for the cation in EMIM-SCN, BMIM-BF4, and BMIM-PF6 are determined. This is done by performing an analysis considering all relevant intra- and intermolecular relaxation contributions to the 1H spin-lattice relaxation as well as by benefiting from the universal low-frequency dispersion law characteristic of Fickian diffusion which yields, at low frequencies, a linear dependence of R1 on square root of frequency. From the 19F relaxation both anion and cation diffusion coefficients are determined for BMIM-PF6. The diffusion coefficients obtained from FC NMR relaxometry are in good agreement with results reported from pulsed- field-gradient NMR. This shows that NMR relaxometry can be considered as an alternative route of determining diffusion coefficients of both cations and anions in ionic liquids.

1.
R.
Kimmich
and
E.
Anoardo
,
Prog. Nucl. Magn. Reson. Spectrosc.
44
,
257
(
2004
).
2.
D.
Kruk
,
A.
Herrmann
, and
E. A.
Rössler
,
Prog. Nucl. Magn. Reson. Spectrosc.
63
,
33
(
2012
).
3.
R.
Meier
,
D.
Kruk
, and
E. A.
Rössler
,
ChemPhysChem
14
,
3071
(
2013
).
4.
A.
Herrmann
,
B.
Kresse
,
B.
Gmeiner
,
A. F.
Privalov
,
D.
Kruk
,
F.
Fujara
, and
E. A.
Rössler
,
Macromolecules
45
,
1408
(
2012
).
5.
B.
Kresse
,
A. F.
Privalov
, and
F.
Fujara
,
Solid State Nucl. Magn. Reson.
40
,
134
(
2011
).
6.
D.
Kruk
,
R.
Meier
, and
E. A.
Rössler
,
J. Phys. Chem. B
115
,
951
(
2011
).
7.
R.
Meier
,
D.
Kruk
,
J.
Gmeiner
, and
E. A.
Rössler
,
J. Chem. Phys.
136
,
034508
(
2012
).
8.
D.
Kruk
,
R.
Meier
, and
E. A.
Rössler
,
Phys. Rev. E
85
,
020201
(
2012
).
9.
A.
Abragam
,
The Principles of Nuclear Magnetism
(
Oxford University Press
,
Oxford
,
1961
).
10.
R.
Meier
,
R.
Kahlau
,
D.
Kruk
, and
E. A.
Rossler
,
J. Phys. Chem. A
114
,
7847
(
2010
).
11.
C. A.
Sholl
,
J. Phys. C
14
,
447
(
1981
).
12.
J. F.
Harmon
,
Chem. Phys. Lett.
7
,
207
(
1970
).
13.
P. H.
Fries
and
E.
Belorizky
,
J. Phys.
39
,
1263
(
1978
).
14.
E.
Belorizky
and
P. H.
Fries
,
J. Phys. C
14
,
L521
(
1981
).
15.
P. H.
Fries
,
Mol. Phys.
48
,
503
(
1983
).
16.
R.
Meier
,
A.
Herrmann
,
M.
Hofmann
,
B.
Schmidtke
,
B.
Kresse
,
A. F.
Privalov
,
D.
Kruk
,
F.
Fujara
, and
E. A.
Rössler
,
Macromolecules
46
,
5538
(
2013
).
17.
L. P.
Hwang
and
J. H.
Freed
,
J. Chem. Phys.
63
,
4017
(
1975
).
18.
Y.
Ayant
,
E.
Belorizky
,
J.
Alizon
, and
J.
Gallice
,
J. Phys. (Paris)
36
,
991
(
1975
).
19.
N. V.
Plechkova
and
K. R.
Seddon
,
Chem. Soc. Rev.
37
,
123
(
2008
).
20.
H.-O.
Hamaguchi
and
R.
Ozawa
,
Adv. Chem. Phys.
131
,
85
(
2005
).
21.
M. N.
Kobrak
,
Adv. Chem. Phys.
139
,
85
(
2008
).
22.
E. W.
Castner
 Jr.
, and
J. F.
Wishart
,
J. Chem. Phys.
132
,
120901
(
2010
).
23.
K.
Hayamizu
,
S.
Tsuzuki
,
S.
Seki
, and
Y.
Umebayashi
,
J. Phys. Chem. B
116
,
11284
(
2012
).
24.
D.
Nama
,
P. G. Anil
Kumar
,
P. S.
Pregosin
,
T. J.
Geldbach
, and
P. J.
Dyson
,
Inorg. Chim. Acta
359
,
1907
(
2006
).
25.
H.
Tokuda
,
K.
Hayamizu
,
K.
Ishii
,
M. A. B. H.
Susan
, and
M.
Watanabe
,
J. Phys. Chem. B
108
,
16593
(
2004
).
26.
T.
Umecky
,
M.
Kanakubo
, and
Y.
Ikushima
,
J. Mol. Liq.
119
,
77
(
2005
).
27.
T.
Umecky
,
M.
Kanabuko
, and
Y.
Ikushima
,
Fluid Phase Equilib.
228–229
,
329
(
2005
).
28.
S.
Gabl
,
O.
Steinhauser
, and
A.
Weingärtner
,
Angew. Chem., Int. Ed.
125
,
9412
(
2013
).
29.
C. P.
Slichter
,
Principles of Magnetic Resonance
(
Springer-Verlag
,
Berlin
,
1990
).
30.
N.
Bloembergen
and
L. O.
Morgan
,
J. Chem. Phys.
34
,
842
(
1961
).
31.
A. G.
Redfield
, in
Encyclopedia of Nuclear Magnetic Resonance
edited by
D. M.
Grant
and
R. K.
Harris
(
Wiley
,
Chichester
,
1996
), p.
4085
.
32.
C. J. F.
Böttcher
and
P.
Bordewijk
,
Theory of Electric Polarization
(
Elsevier
,
Amsterdam
,
1973
), Vol.
2
.
33.
J.
Kowalewski
and
L.
Mäler
,
Nuclear Spin Relaxation in Liquids: Theory, Experiments, and Applications
(
Taylor and Francis
,
New York
,
2006
).
34.
D.
Kruk
,
Theory of Evolution and Relaxation of Multi-Spin Systems
(
Bury St Edmunds
,
Arima
,
2007
).
35.
A.
Rivera
,
A.
Brodin
,
A.
Pugachev
, and
E. A.
Rössler
,
J. Chem. Phys.
126
,
114503
(
2007
).
36.
B.
Schmidtke
,
N.
Petzold
,
B.
Pötzschner
,
H.
Weingärtner
, and
E. A.
Rössler
, “
Relaxation stretching, fast dynamics and activation energy: A comparison of molecular and ionic liquids as revealed by depolarized light scattering
,”
J. Phys. Chem. B
(published online) (
2014
).
37.
H.
Cang
,
J.
Li
, and
M. D.
Fayer
,
J. Chem. Phys.
119
,
13017
(
2003
).
You do not currently have access to this content.