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At the ideal setting, slight flickering of the LED may
be observed. If the LED lights up brightly, the signal
is overloaded.
•
Note down the resonance voltage of the coil U
and the corresponding resonant frequency ν
(see Fig. 6).
•
If an oscilloscope is used the resonance voltage
can be read directly from the scope screen.
•
If 3B NETlog™ is being used, exit oscilloscope
mode and save the results. TH table of meas-
urements displayed can be displayed graphically
by clicking the appropriate button and the peak
can then be marked by means of the cursor. The
resonance voltage for the coil U
played.
•
Repeat the measurement for various frequencies
(in 5 MHz-steps).
R
R
is then dis-
R
Fig. 5 ESR experiment set-up using an oscilloscope
3
3.5 Evaluation
•
Calculate the magnetic field according to the
following equation:
mT
=
⋅
B
. 3
47
U
R
R
V
•
Plot a graph of magnetic field against frequency.
(see Fig. 8)
The relationship between the resonant frequency ν
and the magnetic field at resonance B
μ
ν
⋅
⋅
B
=
g
B
R
R
h
where
J
−
μ
=
⋅
24
. 9
28
10
B
T
−
=
⋅
34
h
. 6
626
10
Js
For electrons in free space the Landé factor g = 2.002
R
is as follows:
R
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