W. Richard Bowen and Nidal Hilal 4

4.4 IMAgINg IN LIqUId ANd THE dETERMINATION OF sURFACE ELECTRICAL 119
F
A
A B
0.3
0.4
C D 0.7
0.4
0.1
0.5
(a)
C D
F E
FIgURE 4.12 Calculated isopotential lines at the entrance to a membrane pore of diameter
0.1 �m. (a) 10 �1 M solution, (b) 10 �2 M solution.
F/R/mN/m
4
2
0
0 20 40
B
Distance/nm
(b)
0.6
0.7
0.9
0.8
AFM data
Best fit constant potential
Best fit constant charge
FIgURE 4.13 Best-fit solutions of theoretical force distance curves to AFM experimental
force distance data for a Desal membrane in 10 �3 M NaCl.
E