Self-organization on Nanoparticle Surfaces for Plasmonic and Nonlinear Optical Applications

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dc.contributor.authorChen, Kaien
dc.contributor.committeechairRobinson, Hans D.en
dc.contributor.committeememberDavis, Richey M.en
dc.contributor.committeememberKhodaparast, Giti A.en
dc.contributor.committeememberHeflin, James R.en
dc.contributor.departmentPhysicsen
dc.date.accessioned2014-03-14T20:20:45Zen
dc.date.adate2010-01-20en
dc.date.available2014-03-14T20:20:45Zen
dc.date.issued2009-12-02en
dc.date.rdate2012-06-22en
dc.date.sdate2009-12-15en
dc.description.abstractThis dissertation is about fabrication and functionalization of metal nanoparticles for use in plasmonic and nonlinear optical (NLO) applications. In the first two chapters, I describe a series of experiments, where I combined silver nanoparticles fabricated by nanosphere lithography with ionic self-assembled multilayer (ISAM) films, tuning the geometry of the particles to make their plasmonic resonances overlap with the frequency of optical excitation. The designed hybrid metallic/organic nanostructures exhibited large enhancements of the efficiency of second harmonic generation (SHG) compared to conventional ISAM films, causing a modified film with just 3 bilayers to be optically equivalent to a conventional 700-1000 bilayer film. SHG responses from Ag nanoparticle-decorated hybrid-covalent ISAM (HCISAM) films were investigated as the next logical step towards high-Ï ²⁺ ISAM films. I found that the plasmonic enhancement primarily stems from interface SHG. Interface effects were characterized by direct comparison of SHG signals from PAH/PCBS ISAM films and PAH/PB HCISAM films. Though interface &chi²⁺ is substantially smaller in PAH/PCBS than in PAH/PB, plasmonically enhanced PAH/PCBS films exhibit stronger NLO response. I propose that the structure of PAH/PB film makes its interface more susceptible to disruptions in the nanoparticle deposition process, which explains our observations. During the fabrication of monolayer crystals for nanosphere lithography, I developed a variation of the technique of convective self-assembly, where the drying meniscus is restricted by a straight-edge located approximately 100 μM above the substrate adjacent to the drying zone. This technique can yield colloidal crystals at roughly twice the growth rate compared to the standard technique. I attribute this to different evaporation rates in the thin wet films in the two cases. I also found that the crystal growth rate depends strongly on the ambient relative humidity. Finally, dithiocarbamate (DTC)-grafted polymers were synthesized and employed to functionalize surfaces of Au nanopartciles. PAH-DTC shows greater stability in different environments than PEI-DTC. I also investigated the stability of PAH-DTC coated particles in suspensions with UV-Vis spectroscopy and autotitration. The covalently bonded PAH-DTC enhances the colloidal stability of the Au nanoparticles and enables subsequent ISAM film deposition onto the particles.en
dc.description.degreePh. D.en
dc.identifier.otheretd-12152009-191229en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-12152009-191229/en
dc.identifier.urihttp://hdl.handle.net/10919/30111en
dc.publisherVirginia Techen
dc.relation.haspartChen_K_D_2009.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectionic self-assembly multilayer (ISAM) filmen
dc.subjectdithiocarbamateen
dc.subjectconvective self-assemblyen
dc.subjectsurface functionalizationen
dc.subjectlocalized surface plasmon resonanceen
dc.titleSelf-organization on Nanoparticle Surfaces for Plasmonic and Nonlinear Optical Applicationsen
dc.typeDissertationen
thesis.degree.disciplinePhysicsen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

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