Presenter: William Crowley
Mentors: Ben Taber and George Nazin, Chemistry
Poster: 15
Major: Chemistry
Scanning tunneling microscopy (STM) can be utilized to image, manipulate, and spectroscopically characterize individual atoms and molecules. The scanning probe used in STM is often described as a tip. Tips are conically shaped pieces of metal that are, ideally, atomically defined at one end. Creating well defined tips is essential to obtaining quality STM images. Due to its spectroscopic enhancing plasmonic properties silver is an interesting material for STM. Specifically, enhancements to the factor of 106 to 107 have been reported. The Nazin group has developed a novel method of electroetching sliver to produce well defined STM tips. In our process we utilize a previously unused electrolyte; 1:8 glacial acetic acid to deionized water. Our two-step process first involves an automated primary electrochemical etch in which a 0.5 mm 9.9985% silver wire is etched to form a rough conical shaped. Second, the roughly shaped silver wire is manually etched to produce a well-defined apex. My research has focused on optimizing and parametrizing variables in this two-step process such as voltage bias and rate of etching. Finished tips are then characterized by scanning electron microscopy and energy dispersive x-ray spectroscopy. This process has yielded tips with an apex of approximately 200 nm.