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Investigation of Thin Molecular Films by Surface Enhanced Vibrational Spectroscopy

by Tian, Hong

Abstract (Summary)
The use of surface enhanced vibrational spectroscopy to characterize structures, investigate interactions at interface and measure thickness of nanocoatings has been investigated. The structural development of pyrolyed photoresist films (PPF) was characterized by both IR and Raman spectroscopy. The physicochemical properties of these films changed as a function of the pyrolysis temperature. PPF pyrolyzed at 1000 ? formed highly defective nanocrystalline carbons with a significant contribution from various sp2, sp3 type carbons and aromatic rings of the original polymer. Dilute solution of photoresist was used as an excellent starting material for the manufacture of optically transparent pyrolyzed photoresist films (OTPPF). OTPPF offers the possibility of sensitive, reproducible, and stable measurements in both UV-Vis and infrared regions of the electromagnetic spectrum. It provides the information of structures of molecules, interaction of adsorbed molecules and the substrate at air-solid interfaces. A study of surface enhanced vibrational spectroscopy on 4-nitroazobenzene (NAB) has been conducted. A new strategy of surface enhanced infrared absorption spectroscopy (SEIRA) has been developed based on the extraordinary transmission effect of metal microarrays. The intensity and position of transmission resonances of double stacked Ni meshes can be tuned by rotating one mesh relative to the other. When the resonances shift to the vibrational frequencies of NAB, the corresponding absorption features are greatly enhanced. Nanocoatings of TiO2 were applied to one side of free standing Ni meshes. Shifts, attenuation and broadening of the transmission resonances have been observed versus coating thickness. New modes have been developed to correlate the optical response of Ni mesh with coating thickness. The Ni meshes exhibit potential as sensors for nanoscale coating thickness.
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Advisor:

School:The Ohio State University

School Location:USA - Ohio

Source Type:Master's Thesis

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ISBN:

Date of Publication:01/01/2008

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