Visualizing Nanoscale Surface Chemistry: From Ultra-High Vacuum to Electrochemical Environments

Erin V. Iski

Charles University Prague, Czechia
Department of Surface and Plasma Science

Tuesday, 22nd March 2022,16:00 s.t.

The talk will be given in a hybrid mode.

You can either join via Zoom:
Meeting ID: 952 2901 0795    Passcode: MtvBD2Y5

Or you attend in physical presence:
TU Wien, Institute of Applied Physics,
Wiedner Hauptstraße 8-10, 1040 Vienna
Yellow Tower “B”, Seminar Room DB 05 B (5th floor)

Visualizing Nanoscale Surface Chemistry: From Ultra-High Vacuum to Electrochemical Environments

Often, pristine molecular resolution on metal surfaces necessitates the use of low temperature, ultra-high vacuum STM (LT-UHV STM). Importantly, it is also possible to study the assembly of molecules and atoms with liquid and electrochemical STM (EC-STM) to bridge the temperature and pressure gap of ultra-high vacuum studies and to take measurements under more realistic conditions. The first investigation focuses on the EC-STM study of five simple amino acids (AAs), and the means by which these molecules interact with a Au(111) surface. Using EC- STM under relevant biological 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 external applied potential. 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. In the second project, EC-STM was used to study the deposition of AAs on an atomically thin layer of Ag on Au(111), which demonstrated extreme surface roughing in stark contrast to the same deposition on bare Au. Despite the periodic familial similarities between Ag and Au, the monolayer of Ag drastically altered the molecule-surface interactions leading to another example of how thin films chemically modify bulk materials.

Bio of Erin V. Iski

Combining aspects from both her graduate work at Tufts and her postdoctoral work at Argonne, Erin Iski‘s research program at TU is centered on the use of ambient, liquid, and electrochemical Scanning Tunneling Microscopy (EC-STM) to study atomically-thin, thermally stable Ag films on Au(111) and the self-assembly of amino acids on metal surfaces. The first project is focused on understanding thin film formation and stability. This second project pertains to the origin of homochirality in biology, the preference for specific secondary structures of proteins, and the characterization of non-covalent supramolecular interactions. The use of ambient and EC-STM utilizes both the incredible molecular and atomic resolution of STM and the ability to apply the findings to real-world applications, since the data is obtained at ambient pressures and temperatures. The Iski lab has developed strong interdisciplinary collaborations in a variety of fields such as nanoscience, engineering, and biochemistry, and the TU Nanotechnology Institute. Students in her research group are trained in highly valuable scientific techniques, exposed to groundbreaking science, and obtain results publishable in notable scientific journals. Other notable collaborations include work with the Jet Propulsion Lab and examining a novel method for analyzing nano-scale surface redox chemistry of prebiotic mineral catalysts and the Erosion/Corrosion Research Center at TU, which is interested in understanding the fundamental principles behind the corrosion of steel.