Tips used in Scanning Tunneling Microscopy (STM) have many requirements in order to make them viable for use in <i>in situ </i>(liquid) and electrochemical STM. First, for STM scanning in general, tips must be metallic and atomically sharp, in order to allow electrons to tunnel from the tip to another metal surface and vice versa when a bias is applied. Once a tip is placed into an electrochemical cell with an electrolyte, faradaic background current from the metallic tip acting as an electrode can overpower the tunneling current; subsequently, tips must be coated in an insulating material that covers the entirety of the tip except for a few bare atoms at the end to allow for tunneling. The production of STM tips via electrochemical etching and the influence of variables, such as voltage, identity of electrolyte, concentration of electrolyte, tip material, and loop material, on the efficacy of etched W tips was investigated. Areas of interest include developing a system to stop current flow once the etching process is complete, thereby preserving two tips and eliminating dullness, as well as developing a “pseudocell” which can be used to eliminate electrically “leaky” or over-coated tips before use on the surface of interest. Verification of tip viability was performed using Scanning Electron Microscopy (SEM) and STM techniques. The chemical mechanism behind the etching procedure was also examined in addition to working on a novel, economical, and easily applied tip coating material. In particular, nanopolymers were examined as a new method of tip insulation.<br/>

Dependable and reproducible procedure for the production of atomically sharp and electrically isolated STM tips

251st National Meeting (2016)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.