This document describes how to import external electrochemical impedance spectroscopy (EIS) data into the Pine Research AfterMath Blue software for analysis (e.g., circuit fitting, graphing). The procedure outlined herein is only valid on AfterMath versions 1.5.XXXXX and later (commonly referred to as “green” AfterMath) as well as newer AfterMath Blue versions 2.1.XXXXX. Earlier versions of the software (i.e., 1.4.XXXXX, 1.3.XXXXX, or 1.2.XXXXX) do not support EIS data generation, import, or analysis.

AfterMath Blue software contains many powerful tools for analyzing electrochemical impedance spectroscopy (EIS) data. Tabulated EIS data collected using a competitor’s potentiostat, or otherwise generated and/or manually fabricated, may be imported into AfterMath Blue quickly and easily. Once imported, analysis can be performed via a number of tools, most notably Circuit Fit or Kramers-Kronig. Imported and analyzed (fitted) data can then be saved, or exported if further analysis/manipulation by another software platform is required.

Click the “File” menu at the top left of the screen in AfterMath Blue, then select the “Import External Data” option (see Figure 1). Alternately, the keystroke CTRL+I may be entered instead. A Multi-Column Data Import dialog box will open (see Figure 2). Click the dropdown next to “Data Specialization” and select the “EIS” option (which assumes frequency values in units of Hz); however, there are several other options in the dropdown menu, including “Mott-Schottky”, and both “EIS” or “Mott-Schottky” where the frequency may be in logarithmic units. For the scope of this document, only the default “EIS” option will be considered.

Figure 1 – AfterMath Blue External Import

Figure 2 – Multi-Column Data Import

One option for importing EIS data into AfterMath Blue is to simply copy and paste multiple columns of data directly into the dialog box. From the raw data file, copy the desired data columns onto the computer’s clipboard, then right-click in the dark gray section of the AfterMath Blue Multi-Column Data Import dialog box and click “Paste” (see Figure 3).

Figure 3 – Copy-Paste EIS Data

The data will appear in the dialog box and AfterMath Blue automatically assigns variables to each column in order based on the typical logical order for EIS data: Frequency (in Hz), Real Impedance (Zr, in Ω), -Imaginary Impedance (-Zi, in Ω), Impedance Magnitude (|Z|, in Ω), then Phase Angle (Φ, in °) (see Figure 4). However, the drop-downs at the top of each column may be adjusted if the raw data columns do not agree with the default variable assignments.

Figure 4 – Pasted 5-Column EIS Data

The list of options for any data column in the dialog box drop-downs includes the five previously-mentioned variables, as well as non-negated Imaginary Impedance (Zi) and , which can be used if additional columns are pasted that do not contain EIS data or are not needed. AfterMath Blue will appropriately skip over any data column with a drop-down set to .

Units for each variable, regardless of their column order in the dialog box, must be as defined above. For example, if the Phase Angle is in units of radians, the raw data must first be converted to degrees before attempting to import. Otherwise, the imported data in AfterMath Blue will be incorrect.

It is not necessary to have all five columns of EIS data for a successful import. Only three columns of EIS data are strictly necessary, though the specific variables for those columns are important. For example, a user may import Frequency, Real Impedance, and Imaginary Impedance (either negated or non-negated), and AfterMath Blue will automatically calculate the respective columns for Impedance Magnitude and Phase Angle. Conversely, a user may import Frequency, Impedance Magnitude, and Phase Angle, and AfterMath Blue will automatically calculate the respective columns for Real Impedance and Imaginary Impedance. Any other combination of EIS variables is not currently supported by the Multi-Column Data Import feature in AfterMath.

Finally, once all necessary columns of EIS data have been pasted and variables appropriately assigned, click the “Import” button at the bottom right of the dialog box. A message will appear to indicate whether the import operation was successful or not. If the operation was successful, a new archive will appear in left tree structure of AfterMath Blue with the imported data and automatically-generated Nyquist and Bode plots (see Figure 5). Additionally, the title of the imported data node will note the method of import. For example, for the previously-described copy/paste method, the title will read “Import from pasted data” (see Figure 5). If the data is imported via CSV file, the title will instead note the filename associated with the EIS data (see Section 3.1.2 for instructions on CSV file import).

Figure 5 – Successful EIS Copy-Paste Import