Stabilizing Nanometer Scale Tip-to-Substrate Gaps in Scanning Electrochemical Microscopy Using an Isothermal Chamber for Thermal Drift Suppression

作者：Kim Jiyeon; Shen Mei; Nioradze Nikoloz; Amemiya Shigeru^*

来源：Analytical Chemistry, 2012, 84(8): 3489-3492.

DOI：10.1021/ac300564g

The control of a nanometer-wide gap between tip and substrate is critical for nanoscale applications of scanning electrochemical microscopy (SECM). Here, we demonstrate that the stability of the nanogap in ambient conditions is significantly compromised by the thermal expansion and contraction of components of an SECM stage upon a temperature change and can be dramatically improved by suppressing the thermal drift in a newly developed isothermal chamber. Air temperature in the chamber changes only at similar to 0.2 mK/min to remarkably and reproducibly slow down the drift of tip-substrate distance to similar to 0.4 nm/min in contrast to 5-150 nm/min without the chamber. Eventually, the stability of the nanogap in the chamber is limited by its fluctuation with a standard deviation of +/- 0.9 nm, which is mainly ascribed to the instability of a piezoelectric positioner. The subnanometer scale drift and fluctuation are measured by forming a similar to 20 nm-wide gap under the 12 nm-radius nanopipet tip based on ion transfer at the liquid/liquid interface. The isothermal chamber is useful for SECM and, potentially, for other scanning probe microscopes, where thermal-drift errors in vertical and lateral probe positioning are unavoidable by the feedback-control of the probe substrate distance.

• 出版日期2012-4-17