| AVS 62nd International Symposium & Exhibition | |
| Spectroscopic Ellipsometry Focus Topic | Thursday Sessions |
| Session EL-ThP |
| Session: | Spectroscopic Ellipsometry Poster Session |
| Presenter: | Derek Sekora, University of Nebraska - Lincoln |
| Authors: | D. Sekora, University of Nebraska - Lincoln A.J. Zaitouna, University of Nebraska - Lincoln R.Y. Lai, University of Nebraska - Lincoln T. Hofmann, University of Nebraska - Lincoln M. Schubert, University of Nebraska - Lincoln E. Schubert, University of Nebraska - Lincoln |
| Correspondent: | Click to Email |
The optical and electrical properties of flat and highly ordered, 3-dimensional nanostructured thin films change dramatically upon adsorption of self assembled monolayers (SAMs) to the surface. Here, a tribrid technique consisting of electrochemistry (EC), quartz crystal microbalance with dissipation (QCM-D), and generalized spectroscopic ellipsometry (GSE) is introduced which allows for fundamental analysis of simultaneous electrochemical, optical, and mechanical properties. The electrochromic reduction of methylene blue terminated SAMs on flat and slanted columnar thin film Au substrates is investigated as an example.
The electrochemical redox reaction of methylene blue produces a switch between a blue and colorless SAM, which can be ellipsometrically modeled. Furthermore, a combinatorial tribrid analysis of in-situ step-decreased constant potential scans elucidate the effects of varying the quantity of reduced methylene blue molecules on flat and nanostructured surfaces. The EC and GSE results imply that methylene blue molecules attached deep between Au slanted columns are not as readily reduced as a result of capacitive shielding effects at lower cell potentials. The concurrent in-situ QCM-D response indicates no quantifiable mass transfer as expressed by the Sauerbrey analysis. The results demonstrate that the fluidic tribrid technique allows characterization of conformal coatings on highly ordered nanostructured surface topographies during electrochemical surface modifications. Our approach is perfectly suited for applications including DNA sensing procedures, electrochemical surface reactions, and surfactant effects.