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Square Wave Voltammetry (SWV)

Last Updated: 10/30/18 by Support

ARTICLE TAGS
  • AfterMath SWV,
  • osteryoung,
  • square wave,
  • square wave voltammetry,
  • SWV
Article Contents/Section Navigation
  1. Technique Overview
  2. Fundamental Equations
  3. Experimental Setup in AfterMath
    1. Basic Tab
    2. Advanced Tab
    3. Ranges, Filters, and Post Experiment Conditions Tab
  4. Sample Experiment
  5. Example Applications
  6. References

1Technique Overview

2Fundamental Equations

3Experimental Setup in AfterMath

To perform a square wave voltammetry experiment in AfterMath, choose Square Wave Voltammetry (SWV) from the Experiments menu (see Figure 1).
 
Square Wave Voltammetry (SWV) Experiment Menu Selection in AfterMath

Figure 1. Square Wave Voltammetry (SWV) Experiment Menu Selection in AfterMath

 
Doing so creates an entry within the archive, called SWV Parameters. In the right pane of the AfterMath application, several tabs will be shown (see Figure 2).
 
Square Wave Voltammetry (SWV) Experiment Basic Tab

Figure 2. Square Wave Voltammetry (SWV) Experiment Basic Tab

 
Continue reading for detailed information about the fields on each unique tab.
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3.1Basic Tab

The basic tab contains fields for the fundamental parameters necessary to perform a SWV experiment.  AfterMath shades fields with yellow when an entry is required and shades the field pink when the entry made is invalid.
Basic tab for Square Wave Voltammetry (SWV) experimental parameters. Inset figure plots each BE period on a time axis

Figure 3. Basic Tab for Square Wave Voltammetry (SWV) Experimental Parameters

 
Square Wave Voltammetry (SWV) Basic Tab Macro Parameters

Figure 4. Square Wave Voltammetry Basic Tab Macro Parameters Waveform Drawing

Square Wave Voltammetry (SWV) Basic Tab Micro Parameters

Figure 5. Square Wave Voltammetry Basic Tab Micro Parameters Waveform Drawing

 
The first set of parameters are the Sweep limits (see Figure 3).  The Sweep limits parameters define the overall (macroscopic) potential vs. time waveform details, such as the number of segments,  initial and final potential values, and other critical parameters (see Figure 4).  Certain fields will not appear unless the number of segments (Sn) dictates their necessity.  There are at least three unique cases for SWV when the number of segments entered will change the fields displayed in the form, as follows:
 
  1. A SWV experiment with one segment (S1) must define initial  potential (EI) and final potential (EF)
  2. A SWV experiment with two segments (S1 and S2) must define initial  potential (EI), vertex potential (EV), and final potential (EF)
  3. A SWV experiment with three or more segments (S1S2, S3, … , Sn) must define initial potential (EI), initial direction (DIRI), upper potential (EU), lower potential (EL), and final potential (EF).
 
The next set of parameters are the Square wave parameters (see Figure 3). The Square wave parameters define the fine (microscopic) waveform/pulse sequence details, such as the wave amplitude and period (see Figure 5).  The square pulse waveform, designed in this section, applies along the macro waveform constructed in the Sweep limits section above (see Figure 4).  The square wave parameters include
 
  1. Amplitude (ESW, A) defines the forward and reverse potential pulse amplitude
  2. Period (TSW, P) defines the time of one complete square wave cycle
  3. Increment (ESW, I) defines potential increase in each period
  4. Sampling width (TSW, I) defines the time at which a single measurement is made in both the forward and reverse directions, measured as the time before the next square pulse
 

HELP  Unfortunately, terms and symbols for electrochemical experimental parameters are not unified across the field, nor across potentiostat and software designers.  Consult the macro and micro waveform plots to better understand the effect of changing experimental parameters.  Feel free to contact us with any questions still unanswered.

 
The Electrode current range K1 section of the basic tab offers the ability to select the initial current range and choose autorange setting.  More information about Electrode range settings can be found in our general AfterMath operations knowledgebase article **.
 
By default, AfterMath performs SWV in the following sequence:  Induction period → Square Wave Voltammetry Period  → Relaxation Period (see Figure 4).
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3.2Advanced Tab

The advanced tab contains fields for the advanced features of the SWV experiment, which include Induction period Induction Period  Relaxation period Relaxation Period and iR Compensation  iR Compensation (see Figure 7).  These advanced features are present for many techniques in AfterMath and are not unique to square wave voltammetry.  Induction and Relaxation periods arise before and after the SWV waveform, established on the Basic tab.  Both potential and duration can be adjusted for either period as shown (see Figure 8).  While tAfterMath inserts these periods into your experiment, data are not measured or recorded during these periods.
 
Induction period, which applies before the waveform begins, has two settings to choose potential (EIND) and duration (TIND).  By default, when "auto" is ticked, the Potential (EIND) will be the same as the initial potential (EI) from the Basic tab and applies for a duration (TIND) 3 s.
 
Relaxation period, which applies after the waveform ends, has two settings to choose potential (ERLX) and duration (TRLX).  By default, when "auto" is ticked, the Potential (ERLX) will be the same as the initial potential (EF) from the Basic tab and applies for a duration (TRLX) 1 s.
 
Square Wave Voltamemtry (SWV) Advanced Tab settings plot

Figure 7. Square Wave Voltammetry (SWV) Advanced Tab

Square Wave Voltamemtry (SWV) Advanced Tab settings plot

Figure 8. Square Wave Voltammetry (SWV) Advanced Tab Settings Plot

 
Additional text
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3.3Ranges, Filters, and Post Experiment Conditions Tab

4Sample Experiment

5Example Applications

6References

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