Document Detail


Forced Convection during Feedback Approach Curve Measurements in Scanning Electrochemical Microscopy (SECM): Maximal Displacement Velocity with a Microdisk.
MedLine Citation:
PMID:  22385037     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
In Scanning Electrochemical Microscopy (SECM), an approach curve performed in feedback mode involves the downward displacement of a microelectrode towards a substrate while applying a bias to detect dissolved electroactive species at a diffusion- limited rate. The resulting measured current is said to be at steady state. In order to reduce the required measurement time, the approach velocity can be increased. In this paper, we investigate experimentally and theoretically the combination of diffusion and convection processes related to a moving microdisk electrode during feedback approaches. Transient modeling and numerical simulations with moving boundaries are performed, and the results are compared to the experimental approach curves obtained in aqueous solution. The geometry and misalignment of the microelectrode influence the experimental approach curves recorded at high approach velocities. The effects are discussed through the decomposition of the current into transient diffusional, radial convectional and axial convectional contributions. Finally a ready-to-use expression is provided to rapidly evaluate the maximal approach velocity for steady state measurements as a function of the microelectrode geometry and the physical properties of the media. This expression holds for the more restrictive case of negative feedback as well as other modes, such as SECM approach curves performed at substrates displaying first order kinetics.
Authors:
Renaud Cornut; Stephanie Poirier; Janine Mauzeroll
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-3-5
Journal Detail:
Title:  Analytical chemistry     Volume:  -     ISSN:  1520-6882     ISO Abbreviation:  -     Publication Date:  2012 Mar 
Date Detail:
Created Date:  2012-3-5     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0370536     Medline TA:  Anal Chem     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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