VIII.
MAGNETIC RESONANCE
J. W. Riehl
C. G. Wade
D. W. Schaefer
Prof. J. S. Waugh
Dr. J. Rugheimer
Dr. R. Newmark
J. D. Macomber
A.
D.
E.
A.
E.
S. Thompson
T. Stone
Leonardi
L. Wei
SELF-DIFFUSION IN LIQUID ETHANE
Measurements have been completed of the self-diffusion coefficient D of liquid C H 6
at temperatures between 1550 and 298°K and between 1 and 2500 atm (Fig. VIII-1).
4
3
2
x
x
0.9
298K
284°K
*
0.8
E
S07
o
0.6 -
*
.
265°K
2550K
x
200
600
1000
1400
1800
PRESSURE IN ATMOSPHERES
QPR No. 77
2200
2600
Fig. VIII-1.
Dependence of the self-diffusion
coefficient D in ethane on pres sure at various constant temperatures.
(VIII.
MAGNETIC RESONANCE)
Proton spin echoes were used for this purpose.1
The equation of state was determined
very approximately by measuring the pressure dependence of free-induction decay amplitudes at various constant temperatures.
Thus it was possible to show (as anticipated)
that the free-volume theory, which could be used to fit our earlier results at constant
the experimental density dependence. Figure VIIIpressure, 2 is
is inconsistent
inconsistent with
with the experimental density dependence. Figure VIII-2 shows
EXPERIMENTAL
0.4
0.2
-0.2
DENSITY=0.65
-0.4
-0.6
I
I
6
I I
I
9
I
12
S(oK
Fig. VIII-2.
I I
3
g/cm
I
I 1
1
15
1/2
Experimental and theoretical values of D at constant volume.
representative results reduced to constant density.
The circles are experimental points.
The dotted and dashed lines show the predictions of the Doolittle 3 and of the CohenTurnbull 4 versions of free-volume theory,
measurements at constant pressure
with the parameters that fit our previous
used.
C.
G. Wade,
J.
S. Waugh
References
E. L. Hahn, Phys. Rev. 80, 580 (1950).
J. V. Gaven, W. H. Stockmayer, and J. S. Waugh, J. Chem. Phys. 37, 1188 (1962).
A. K. Doolittle, J. Appl. Phys. 22, 1471 (1951).
M. H. Cohen and D. Turnbull, J. Chem. Phys. 31,
QPR No. 77
1164 (1959).