Scanning electrochemical microscopy

Abstract

A new scanning electrochemical microscopy tip positioning method that allows topography and surface activity to be resolved independently is presented. A SECM tip is oscillated relative to the surface of interest. Changes in the oscillation amplitude, caused by the intermittent contact of the SECM tip with the surface of interest, are used to detect the surface of interest, and as a feedback signal for various types of imaging.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]The present application is a national phase filing, under 35 U.S.C. §371(c), of International Application No. PCT / GB2011 / 050747, filed Apr. 14, 2011, the disclosure of which is incorporated herein by reference in its entirety.FIELD OF THE INVENTION[0002]This invention relates to scanning microscopy.BACKGROUND TO THE INVENTION[0003]Scanning electrochemical microscopy (SECM) is a scanned probe microscopy to technique in which the electrochemical response of a SECM tip (typically an ultramicroelectrode (UME) with an active part of less than 25 μm) is used to provide information on the properties (e.g. topography or chemical activity) of a surface of interest (an interface, surface or phase) or for modification of a surface of interest (an interface, surface or phase). The SECM tip is immersed in a solution and used to detect chemical species (molecules or ions) which interact with the SECM tip or to generate chemical species (molecules or ion...

AI Technical Summary

Benefits of technology

[0035]The invention, some aspects of which are known as intermittent contact SECM (IC-SECM), is a new scanning microscopy, for instance SECM, tip positioning method that can allow topography and surface activity to be resolved independently.

[0038]Compared to existing techniques, embodiments of this invention provide an inexpensive, robust and simple method to independently resolve substrate topography and surface activity. Minimal additional equipment and control schemes are needed to implement certain embodiments of the invention. Thus, aspects of the invention provide an inexpensive and simple method to resolve substrate topography and substrate activity in SECM. The feedback (used to locate the surface) depends on the physical interaction of the SECM tip with the substrate surface and does not depend on the surface activity. This means that changes in substrate activity do not affect the tip-substrate distance measurements, and thus embodiments of the invention provide a robust method to determine substrate topography and substrate activity independently. This also means that aspects of the invention can be used with standard SECM tips (UMEs) and in standard SECM modes. Aspects of the invention can be used also in non-electrochemical microscopy.

[0039]A particularly attractive feature of this approach is that it would allow other types of SECM tips, such as potentiometric electrodes and ion conductance probes, to be deployed. Also because the tip position is oscillated slightly, one can additionally isolate the ac component of the current as well as the mean current, greatly enhancing the electrochemical information content.

Problems solved by technology

Despite the tremendous impact of SECM in interfacial science, a significant—and generally unresolved—challenge concerns absolute tip positioning.

However, it can be difficult to find appropriate redox-active species that do not interact with the underlying system of interest when using two mediators.

Images