KSV SPOT
KSV SPOT Manual
Rev. 1.0
18
7. Example measurements
Stearic acid has been used as the monolayer forming substance because it has been studied by
a large number of research groups and its characteristic properties are largely known. In these
example measurements a pure water subphase with pH = 4 have been used. The obtained
surface potential values are 349 ± 2 mV. This is in good accordance with the literature values.
The reproducibility of the KSV SPOT measuring head is very good which is seen from the
low standard deviation of the results.
Surface pressure and Surface potential isotherm of´ Stearic acid on a subphase with pH = 4.
Three separate measurements of Stearic acid monolayers on a water subphase (pH = 4)
demonstrating the reproducibility of the KSV SPOT surface potenital measuring head.
10
20
30
40
50
0
10
20
30
40
50
60
S
u
rf
a
c
e
p
o
te
n
tia
l [
m
V
]
S
u
rf
a
c
e
p
re
s
s
u
re
[
m
N
/m
]
Mean molecular area [Å
2
/m olecule]
0.0
0.1
0.2
0.3
0.4
π
∆
V
10
20
30
40
50
0.0
0.1
0.2
0.3
0.4
S
u
rf
a
c
e
p
o
te
n
ti
a
l
[m
V
]
Mean molecular area [Å
2
/molecule]
