Measuring diffusion in supercooled liquids: The effect of kinetic inhomogeneities (original) (raw)
Research Article| February 08 1996
Department of Physical and Theoretical Chemistry, University of Sydney, NSW 2006, Australia
Search for other works by this author on:
Department of Physical and Theoretical Chemistry, University of Sydney, NSW 2006, Australia
Search for other works by this author on:
J. Chem. Phys. 104, 2369–2375 (1996)
There is growing evidence to suggest that cooperativity in glasses is characterized by a spatial distribution of relaxation times. In this paper we examine the consequences of such inhomogeneities in the measurement of translational and rotational diffusion constants. We find that the decay of a concentration profile (the basis of transient grating experiments) is accelerated by the development of additional gradients parallel to the relaxation time gradients. This may account for recently observed differences in the variation of rotational and translational diffusion constants with viscosity below the glass transition temperature. The additional gradients may also provide the first direct means of examining the length scale associated with these inhomogeneities.
REFERENCES
S.
Butler
and
P.
Harrowell
,
J. Chem. Phys.
95
,
4454
(
1991
).
P.
Harrowell
,
Phys. Rev. E
48
,
4359
(
1993
).
M.
Foley
and
P.
Harrowell
,
J. Chem. Phys.
98
,
5069
(
1993
).
M. M.
Hurley
and
P.
Harrowell
,
Phys. Rev. E
52
,
1694
(
1995
).
R.
Moss
and
P.
Harrowell
,
J. Chem. Phys.
101
,
9894
(
1994
).
C. T.
Moynihan
and
J.
Schroeder
,
J. Non-Cryst. Solids
160
,
52
(
1993
).
G.
Adam
and
J. H.
Gibbs
,
J. Chem. Phys.
43
,
139
(
1965
).
E. W.
Fischer
,
E.
Donth
, and
W.
Steffen
,
Phys. Rev. Lett.
68
,
2344
(
1992
).
M. T.
Cicerone
,
F. R.
Blackburn
, and
M. D.
Ediger
,
J. Chem. Phys.
102
,
471
(
1995
).
K.
Schmidt-Rohr
and
H. W.
Spiess
,
Phys. Rev. Lett.
66
,
3020
(
1991
).
J. A.
Hodgdon
and
F. H.
Stillinger
,
Phys. Rev. E
48
,
207
(
1993
).
F. H.
Stillinger
and
J. A.
Hodgdon
,
Phys. Rev. E
50
,
2064
(
1994
).
J. T.
Bendler
and
M. F.
Shlesinger
,
J. Phys. Chem.
96
,
3970
(
1992
);
J. T.
Bendler
and
M. F.
Shlesinger
,
J. Mol. Liq.
36
,
37
(
1987
);
J. T.
Bendler
and
M. F.
Shlesinger
,
J. Stat. Phys.
53
,
531
(
1988
).
J. Y.
Caveille
,
J.
Perez
, and
G. P.
Johari
,
Phys. Rev. B
39
,
2411
(
1989
).
D.
Ehlich
and
H.
Sillescu
,
Macromolecules
23
,
1600
(
1990
).
F.
Lanni
and
B. R.
Ware
,
Rev. Sci. Instrum.
53
,
905
(
1982
).
F.
Fujara
,
B.
Geil
,
H.
Sillescu
, and
G.
Fleisher
,
Z. Phys. B: Condens. Matter
88
,
195
(
1992
);
see also M. Lohfink and H. Sillescu, in Slow Dynamics in Condensed Matter, AIP Conf. Proc. 256, edited by K. Kawasaki, M. Tokuyama, and T. Kawakatsu (AIP, New York, 1992), p. 30.
C. A.
Angell
,
J. Non Cryst. Solids
73
,
1
(
1975
).
D. N. Perera and P. Harrowell, Phys. Rev. E (submitted).
G.
Tarjus
and
D.
Kivelson
[
J. Chem. Phys.
103
,
3071
(
1995
)] have recently argued that the decoupling of translational diffusion from the shear viscosity arises as a consequence of the averaging over domains in the supercooled liquid. We are unclear as to exactly how the averaging leads to this decoupling, particularly as the authors neglect the gradients of diffusion constants, the very terms which, in this study, couple to concentration gradients to produce the enhanced translational diffusion.
This content is only available via PDF.
© 1996 American Institute of Physics.
1996
American Institute of Physics
You do not currently have access to this content.
Sign in
Sign In
You could not be signed in. Please check your credentials and make sure you have an active account and try again.
Username ?
Password
Pay-Per-View Access
$40.00