Analysis techniques are needed to determine the quantity and structure of materials composing an organic layer that is below an ultra-thin film limit and in a liquid environment. Neither optical nor acoustical techniques can independently distinguish between thickness and porosity of ultra-thin films due to parameter correlation. A combined optical and acoustical approach yields sufficient information to determine both thickness and porosity. We describe application of the combinatorial approach to measure single or multiple organic layers when the total layer thickness is small compared to the wavelength of the probing light. The instrumental setup allows for simultaneous in situ spectroscopic ellipsometry and quartz crystal microbalance dynamic measurements, and it is combined with a multiple-inlet fluid control system for different liquid solutions to be introduced during experiments. A virtual separation approach is implemented into our analysis scheme, differentiated by whether or not the organic adsorbate and liquid ambient densities are equal. The analysis scheme requires that the film be assumed transparent and rigid (non-viscoelastic). We present and discuss applications of our approach to studies of organic surfactant adsorption, self-assembled monolayer chemisorption, and multiple-layer target DNA sensor preparation and performance testing.

Generalized ellipsometry in-situ quantification of organic adsorbate attachment within slanted columnar thin films" (2012 Abstract:We apply generalized ellipsometry, well-known to be sensitive to the optical properties of anisotropic materials, to determine the amount of fibronectin protein that adsorbs onto a Ti slanted columnar thin film from solution. We find that the anisotropic optical properties of the thin film change upon organic adsorption. An optical model for ellipsometry data analysis incorporates an anisotropic Bruggeman effective medium approximation. We find that differences in experimental data from before and after fibronectin adsorption can be solely attributable to the uptake of fibronectin within the slanted columnar thin film. Simultaneous, in-situ generalized ellipsometry and quartz crystal microbalance measurements show excellent agreement on the amount and rate of fibronectin adsorption. Quantitative characterization of organic materials within three-dimensional, optically anisotropic slanted columnar thin films could permit their use in optical sensor applications.

No abstract

No abstract

Three-dimensional inorganic nanostructured thin films with slanted columnar morphologies are functionalized with organic polymer brushes to fabricate a nanohybrid functional material. Nanostructured thin films are fabricated by glancing angle deposition of silicon onto silicon or gold to produce slanted columnar thin films (SCTFs). Polymer brushes are regarded as very promising nanomaterials for surface coatings because these systems are capable of responding to external stimuli such as temperature or pH, generally by reversible swelling/deswelling behavior. The fabrication of the SCTF as well as the stepwise reactions of poly(acrylic acid) guiselin polymer brushes to the SCTF nanocolumns are characterized with generalized ellipsometry and scanning electron microscopy. This study demonstrates that SCTFs are capable of withstanding the polymer brush grafting-to process and that both ellipsometry and electron microscopy indicate polymer brush immobilization within the void spaces of the SCTF. Furthermore, in situ combinatorial ellipsometry and quartz crystal microbalance with dissipation both reveal that the brushes retain their ability to swell/deswell with changes in pH of buffer solution. These tunable nanohybrid functional materials with increased surface area, complex columnar geometries, and stimuliresponsive characteristics provide novel material surfaces for nanoelectronics, biotechnology, and a variety of other advanced material applications.