Session: Undergraduate Research Posters: Nanochemistry:

Obtaining a better understanding of the interaction between biological molecules and metal surfaces is important in an array of fields such as biosensors, solar cells, and the origins of homochirality. Previous studies were conducted at ambient conditions using Electrochemical Scanning Tunneling Microscopy (EC-STM) where amino acids were deposited on a Au(111) surface. It was found that the amino acids form one Au atom high islands on the surface with the island area increasing as a function of molecular weight of the amino acids. Furthermore, the islands exhibit a Volmer-Weber growth mode when raising the surface temperature due to the increased mobility of the Au surface adatoms.
Another interesting system of study is a Ag monolayer on Au(111). Underpotential Deposition (UPD) was used to apply a single layer of Ag atoms to the surface from a silver halide solution in one of two different potential regions. Only one of these two potential regions resulted in a Ag thin film that was thermally stable at 1,000 K. While the Ag monolayer exhibits thermal stability, another facet to consider is its chemical stability, which can be investigated using amino acids. In contrast to amino acids on a bare Au(111) surface, L-Isoleucine on a Ag monolayer resulted in a distinctly different surface morphology with the amino acids etching into the surface. This etching occurred in increments of Au atomic steps and it is proposed that it results from the nitrogen and oxygen atoms of the amino acids chelating Au atoms. This non-traditional growth mode has the potential to be used as a mild method to etch Au, as opposed to conventional methods that use harsh acids and high potentials and provides a greater understanding of the chemistry of Ag thin films.

Erin Iski

University of Tulsa

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