Embedded Files
This downloadable virtual instrument (VI) for scanning electrochemical microscopy (SECM) researchers allows the user to perform simulations and analysis of SECM approach curves.
Downloads
PAC_Fit.zip - .ZIP file that contains main VI (PAC_Fit.vi) and all associated sub-VIs. (Requires LabVIEW version 2010 or higher.)
PAC_Fit_Exe.zip - .ZIP file that contains installer for an executable version (PAC_Fit.exe) of the VI that doe not require LabVIEW. The LabVIEW 2010 SP1 runtime engine is required and is installed as well. (Click file link, download file, then run Setup.exe.)
Sample data - Probe approach data taken with an insulating substrate in 1 mM ferrocene methanol / 0.1 M Na2SO4 / 0.05 M H2SO4. (Click file link, download file, save locally, then load into VI with "Load Data File" button.)
Description
PAC_Fit is a LabVIEW virtual instrument (VI) designed for simulation and analysis of probe approach curve data obtained from a scanning electrochemical microscope. The data may be fit to theory to obtain the absolute height of the probe electrode above a substrate and/or the apparent electron transfer rate constant (kapparent) of the substrate. SECM theory is described in the reference given at the bottom of the page.
The VI accepts text data from a CH Instruments 900B using the text file format shown in the image below. A sample data set is available from the list of downloadable files above.
Front panel of the LabVIEW VI
VI parameters
Electrode radius (a) - radius of the ultramicroelectrode
ibulk - Probe current value in bulk solution (probe positioned at an infinite distance above the substrate)
Diff Coeff (D) - Diffusion coefficient of the mediator
z-offset - Actual height of the probe above the substrate when x = 0 in the raw data file
d - Actual height of the probe above the substrate during approach
L - Normalized height of the probe above the substrate (L = d/a)
Lupper limit - Highest value of L used in theoretical fitting of the data. Note that the SECM theory utilized in this application is only valid for L less than or equal to 2.0.
RG value - Ratio of glass sheath radius to electrode radius. Note that fitting data to determine a heterogeneous rate constant is only valid for RG = 10.
kapparent - Value of the apparent heterogeneous electron transfer rate constant
References
M.V. Mirkin and Y. Wang, "Theory," in Scanning Electrochemical Microscopy, 2nd Ed; A.J. Bard and M.V. Mirkin, Eds; CRC Press: Boca Raton, FL, 2012, pp 75-125.
M.B. Jensen and D.E. Tallman, "A LabVIEW-based virtual instrument for simulation and analysis of SECM approach curves," Journal of Solid State Electrochemistry, 17 (2013) 2999-3003.
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