Browsing by Subject "Interference"

Now showing 1 - 3 of 3
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    Solving the two-interface problem in vibrational sum frequency generation spectroscopy applied to multilayer thin film systems
    (2014-03) O'Brien, Daniel Bruce
    This dissertation describes advances made in applying sum frequency generation spectroscopy (SFG, in particular vibrational SFG or VSFG) to multilayer thin film systems. Application of VSFG to thin film systems is motivated by the challenge of characterizing molecular structure at the active boundary in organic field-effect transistors, these are inherently buried interfaces. VSFG is a surface-selective probe of molecular structure; however, when VSFG is applied to an organic thin film, the detected signal has contributions from two potential sources - the two interfaces of the organic - which must be separated. The problem is further confounded by optical interferences inherent in multilayer thin film systems. An intuitive mathematical model is developed; postulating a solution to the two-interface problem of SFG applied to planar and stratified multilayer structures. The model system for this dissertation is thin films of the small molecule N,N'-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C8) vapor deposited on silica thin film substrates, consistent with an oFET thin film geometry. The interference model is used for an extensive simulation analysis that reveals intricacies contained in the intensity data of VSFG applied to that system. VSFG experiments performed on samples with PTCDI-C8 deposited as gradient thicknesses provide compelling evidence that the model gives an accurate description of optical interference effects and that it can be used to separate contributions to the total VSFG signal intensity. The supplementary materials contain a collection of Mathematica notebooks that can be used to investigate optical interference effects on SFG data collected from systems composed of an arbitrary number of thin film layers.
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    Template-stripped plasmonic cup resonators for single-nanohole-based sensing and spectroscopy
    (2015-05) Olson, Stephen Andrew Olaf
    We have designed and tested a new plasmonic biosensor, featuring a centered nanohole in the base of a recessed metallic nanocup. This configuration enables us to perform independent plasmon-resonance-enhanced single-nanohole transmission spectroscopy on femtoliter volumes of solution. In this thesis we will demonstrate the fabrication, characterization, and application of these novel cup resonator plasmonic biosensors. Utilizing plasmonic confinement to enhance and modulate transmission through a nanohole aperture, the resulting transmission spectra can be used to determine changes in the material properties of a dielectric material located inside the sensing volume of the cup. We have determined, through measurements and simulations, the physical mechanisms causing transmission modulation through the structure. Utilizing this information, we have constructed predictive behavior models for the design and customization of these devices for specific purposes. We show that these structures are responsive to refractive index changes in their surroundings, and propose some possible application of these resonators in biological sensing roles which take advantage of their unique geometry.
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    Tinguely
    (2010-05) Tsuda, Schuyler
    Tinguely is a musical composition scored for strings, percussion and built instruments that focuses on the acoustic phenomena of interference and beats. Instrumental techniques have been developed to produce a sound world largely comprised of acoustic beating, pulsating multiphonics and noise. Instruments have been built or modified to create a timbral transition from strings to metal percussion, and multiple preparations are used on each instrument throughout the piece in order to interfere with its normal method of sound production. The interferences in Tinguely also occur on a metaphorical level, as established repeated musical patterns are disrupted by truncation, extension, silence and chaotic transformation.