Power saturation analysis¶
A crucial step when recording cw-EPR spectra is to optimise the microwave power and to prevent saturation from distorting the signal shape. Therefore, usually a power saturation analysis is conducted, i.e. recording a series of spectra with systematically varying the microwave power.
From the resulting data, the EPR signal amplitude is extracted and plotted as function of the square root of the microwave power. As long as no saturation is occurring, there should be a linear dependency between signal amplitude and square root of microwave power. To further help with analysis, a linear regression covering the first n points can be performed and the results plotted together with the power saturation curve on one figure.
Complete recipe for a power saturation analysis, including plotting the results.¶
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type: ASpecD recipe
version: '0.2'
settings:
default_package: cwepr
autosave_plots: false
directories:
datasets_source: ../../tests/io/testdata/
datasets:
- BDPA-2DFieldPower
tasks:
- kind: processing
type: BaselineCorrection
- kind: singleanalysis
type: AmplitudeVsPower
apply_to:
- BDPA-2DFieldPower
result: power_sweep_analysis
- kind: singleanalysis
type: FitOnData
properties:
parameters:
order: 1
points: 5
return_type: dataset
apply_to:
- power_sweep_analysis
result: fit
comment: Linear fit covering the first five data points.
- kind: multiplot
type: PowerSweepAnalysisPlotter
properties:
properties:
drawings:
- marker: '*'
- color: red
grid:
show: true
axis: both
axes:
title: Overview
ylabel: '$EPR\ amplitude$'
yticklabels: []
apply_to:
- power_sweep_analysis
- fit
result: overview
- kind: multiplot
type: PowerSweepAnalysisPlotter
properties:
properties:
drawings:
- marker: '*'
- color: red
grid:
show: true
axis: both
axes:
title: Detailed view
xlim: [0, 1.65]
ylim: [0, 70]
ylabel: '$EPR\ amplitude$'
yticklabels: []
apply_to:
- power_sweep_analysis
- fit
result: details
- kind: compositeplot
type: CompositePlotter
properties:
plotter:
- overview
- details
filename: power_sweep_analysis.pdf
caption:
title: Power saturation analysis.
text: >
The left panel provides an overview of the entire measurement,
while the right panel provides a detailed view of the first points,
showing that 1 mW of microwave power already starts to saturate the
cw-EPR signal.
grid_dimensions: [1, 2]
subplot_locations:
- [0, 0, 1, 1]
- [0, 1, 1, 1]
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