SECM height relief with OSP: An application in corrosion – Scanning Probes – Application Note 2

Abstract

The response of the Scanning ElectroChemical Microscope (SECM) depends on the surface conductivity of the sample as well as its topography, or more precisely the distance between the probe and the sample. In some cases where the sample is uneven or too rough, the change of response due to the topography is higher the change of response due to conductivity. Measurements in constant distance mode are then needed.

Introduction

The importance of Scanning Electrochemical Microscopy (SECM) to corrosion applications is of growing interest to both scientific and commercial sectors. SECM’s high resolution capabilities coupled with its quantitative analytical capabilities provide a novel method to interrogate and image a surface’s corrosion resistance. Until lately, this technique’s seemingly ideal application has been hampered by the often large topological features in a sample’s surface, rendering the constant-height area scan (where the probe remains at a fixed vertical position above the sample) useful in only a limited range of samples or limited areas of samples. The combination of the Optical Surface Profiling (OSP) technique with the SECM allows a user to take a topographical measurement of the surface features and relieve the SECM probe’s position during the scan. Without the Height-Tracking feature, the current measured across a surface can be influenced by the topography and the electrochemical activity, producing a response that is a sum of both. With the addition of Height-Tracking, it is possible to effectively remove the effects of topography resulting in an unbiased measure of the electrochemical activity

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