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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.
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format:
  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: PolynomialFitOnData
  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]