AVS 66th International Symposium & Exhibition
    Surface Science Division Thursday Sessions
       Session SS+AS+HC+TL-ThM

Paper SS+AS+HC+TL-ThM11
Interaction of Amino Acids on Au(111) as Studied with EC-STM: From Islands to Magic Fingers

Thursday, October 24, 2019, 11:20 am, Room A220-221

Session: Surface Science of Energy Conversion and Storage
Presenter: Erin Iski, University of Tulsa
Authors: J.A. Phillips, University of Tulsa
K.P. Boyd, University of Tulsa
I. Baljak, University of Tulsa
L.K. Harville, University of Tulsa
E.V. Iski, University of Tulsa
Correspondent: Click to Email
With growing interest into origin of life studies as well as the advancement of medical research using nanostructured architectures, investigations into amino acid interactions have increased heavily in the field of surface science. Amino acid assembly on metallic surfaces is typically investigated with Scanning Tunneling Microscopy (STM) at low temperatures (LT) and under ultra-high vacuum (UHV), which can achieve the necessary resolution to study detailed molecular interactions and chiral templating. However, in only studying these systems at LT and UHV, results often tend to be uncertain when moving to more relevant temperatures and pressures. This investigation focuses on the Electrochemical STM (EC-STM) study of five simple amino acids (L-Valine, L-threonine, L-Isoleucine, L-Phenylalanine, and L-Tyrosine) as well as two modifications of a single amino acid (L-Isoleucine Ethyl Ester and N-Boc-L-Isoleucine), and the means by which these molecules interact with a Au(111) surface. Using EC-STM under relevant experimental conditions, the amino acids were shown to have a considerable interaction with the underlying surface. In some cases, the amino acids trapped diffusing adatoms to form Au islands and in other cases, they assisted in the formation of magic gold fingers. Importantly, these findings have also been observed under UHV conditions, but this is the first demonstration of the correlation in situ and was controlled via an applied external potential. Results indicate that an increase in the molecular weight of the amino acid had a subsequent increase in the area of the islands formed. Furthermore, by shifting from a nonpolar to polar side chain, island area also increased. By analyzing the results gathered via EC-STM at ambient conditions, fundamental insight can be gained into not only the behavior of these amino acids with varied side chains and the underlying surface, but also into the relevance of LT-UHV STM data as it compares to data taken in more realistic scenarios.