Nanoscale Intelligent Imaging Based on Real-Time Analysis of Approach Curve by Scanning Electrochemical Microscopy
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Issue Date
2019-07-16Author
Balla, Ryan J.
Jantz, Dylan
Kurapati, Niraja
Chen, Ran
Leonard, Kevin Charles
Amemiya, Shigeru
Publisher
American Chemical Society
Type
Article
Article Version
Scholarly/refereed, author accepted manuscript
Rights
Copyright © 2019 American Chemical Society
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Show full item recordAbstract
Scanning electrochemical microscopy (SECM) enables high-resolution imaging by examining the amperometric response of an ultramicroelectrode tip near a substrate. Spatial resolution, however, is compromised for non-flat substrates, where distances from a tip far exceed the tip size to avoid artifacts caused by the tip–substrate contact. Herein, we propose a new imaging mode of SECM based on real-time analysis of approach curve to actively control nanoscale tip–substrate distances without contact. The power of this software-based method is demonstrated by imaging an insulating substrate with step edges using standard instrumentation without combination of another method for distance measurement, e.g., atomic force microscopy. An ~500 nm-diameter Pt tip approaches down to ~50 nm from upper and lower terraces of a 500 nm-height step edge, which are located by real-time theoretical fitting of experimental approach curve to ensure the lack of electrochemical reactivity. The tip approach to step edge can be terminated at <20 nm prior to the tip–substrate contact as soon as the theory deviates from the tip current, which is analyzed numerically afterward to locate the inert edge. The advantageous local adjustment of tip height and tip current at the final point of tip approach distinguishes the proposed imaging mode from other modes based on standard instrumentation. In addition, the glass sheath of Pt tip is thinned to ~150 nm to rarely contact the step edge, which is unavoidable and instantaneously detected as an abrupt change in the slope of approach curve to prevent the damage of fragile nanotip.
Description
This document is the Accepted Manuscript version of a Published Work that appeared in final form in Analytical Chemistry, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acs.analchem.9b02361.
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Citation
Balla, R. J., Jantz, D. T., Kurapati, N., Chen, R., Leonard, K. C., & Amemiya, S. (2019). Nanoscale Intelligent Imaging Based on Real-Time Analysis of Approach Curve by Scanning Electrochemical Microscopy. Analytical chemistry, 91(15), 10227–10235. doi:10.1021/acs.analchem.9b02361
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