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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.
 1format:
 2  type: ASpecD recipe
 3  version: '0.2'
 4
 5settings:
 6  default_package: cwepr
 7  autosave_plots: false
 8
 9directories:
10  datasets_source: ../../tests/io/testdata/
11
12datasets:
13- BDPA-2DFieldPower
14
15tasks:
16- kind: processing
17  type: BaselineCorrection
18- kind: singleanalysis
19  type: AmplitudeVsPower
20  apply_to:
21  - BDPA-2DFieldPower
22  result: power_sweep_analysis
23- kind: singleanalysis
24  type: FitOnData
25  properties:
26    parameters:
27      order: 1
28      points: 5
29      return_type: dataset
30  apply_to:
31  - power_sweep_analysis
32  result: fit
33  comment: Linear fit covering the first five data points.
34- kind: multiplot
35  type: PowerSweepAnalysisPlotter
36  properties:
37    properties:
38      drawings:
39        - marker: '*'
40        - color: red
41      grid:
42        show: true
43        axis: both
44      axes:
45        title: Overview
46        ylabel: '$EPR\ amplitude$'
47        yticklabels: []
48  apply_to:
49  - power_sweep_analysis
50  - fit
51  result: overview
52- kind: multiplot
53  type: PowerSweepAnalysisPlotter
54  properties:
55    properties:
56      drawings:
57        - marker: '*'
58        - color: red
59      grid:
60        show: true
61        axis: both
62      axes:
63        title: Detailed view
64        xlim: [0, 1.65]
65        ylim: [0, 70]
66        ylabel: '$EPR\ amplitude$'
67        yticklabels: []
68  apply_to:
69  - power_sweep_analysis
70  - fit
71  result: details
72- kind: compositeplot
73  type: CompositePlotter
74  properties:
75    plotter:
76    - overview
77    - details
78    filename: power_sweep_analysis.pdf
79    caption:
80      title: Power saturation analysis.
81      text: >
82        The left panel provides an overview of the entire measurement, 
83        while the right panel provides a detailed view of the first points,
84        showing that 1 mW of microwave power already starts to saturate the
85        cw-EPR signal.
86    grid_dimensions: [1, 2]
87    subplot_locations:
88    - [0, 0, 1, 1]
89    - [0, 1, 1, 1]