| AVS 57th International Symposium & Exhibition | |
| Spectroscopic Ellipsometry Focus Topic | Thursday Sessions |
| Session EL+AS+EM+MS+TF-ThA |
| Session: | Spectroscopic Ellipsometry |
| Presenter: | K.B. Rodenhausen, University of Nebraska-Lincoln |
| Authors: | K.B. Rodenhausen, University of Nebraska-Lincoln B.A. Duensing, University of Nebraska-Lincoln A.K. Pannier, University of Nebraska-Lincoln M. Schubert, University of Nebraska-Lincoln M. Solinsky, The Procter & Gamble Company T.E. Tiwald, J. A. Woollam Co., Inc. |
| Correspondent: | Click to Email |
We report a combinatorial approach to study ultra-thin organic films. This novel technique consists of in-situ spectroscopic ellipsometry and quartz crystal microbalance methods. In contrast to the quartz crystal microbalance, which is sensitive to the total mass attached to the surface, including the trapped solvent, spectroscopic ellipsometry only measures the amount of adsorbent on the surface. We also introduce a new “virtual separation approach” (2πnd/λ ≪ 1 ) of analysis for the ellipsometry measurements. By using these two techniques in tandem, we are able to determine the thickness and solvent fraction of viscoelastic thin films.
We investigate cetyltrimethylammonium bromide (CTAB) thin films deposited onto a gold-coated quartz crystal as a model system. CTAB grown from a 2.5 mM solution demonstrates several phases in porosity evolution, including a temporary hold in water fraction as the film is rinsed off the substrate with water; these effects may be related to the structure of a CTAB bilayer.
In addition, a variety of self-assembled monolayers (SAMs) of alkanethiols on gold-coated quartz crystals are used as model biomaterials to determine the water fraction of an adsorbed prion layer. The porosity information distinguishes the proteins’ conformation, dictated by the defined surface chemistries of the SAMs.