title: Impedance feedback control for scanning electrochemical microscopy.
abstract: A new constant-distance imaging method based on the relationship between tip impedance and tip-substrate separation has been developed for the scanning electrochemical microscope. The tip impedance is monitored by application of a high-frequency ac voltage bias between the tip and auxiliary electrode. The high-frequency ac current is easily separated from the dc-level faradaic electrochemistry with a simple RC filter, which allows impedance measurements during feedback or generation/collection experiments. By employing a piezo-based feedback controller, we are able to maintain the impedance at a constant value and, thus, maintain a constant tip-substrate separation. Application of the method to feedback and generation/collection experiments with tip electrodes as small as 2 microm is presented.
authors.affiliation: Department of Chemistry, Mississippi State University, Mississippi State 39762, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Alpuche-Aviles
authors.forename: D O
authors.initials: DO
authors.lastname: Wipf