Date of Award

5-2011

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Chemistry

Major Professor

Michael J. Sepaniak

Committee Members

David Joy, Frank Vogt, Ziling Xue

Abstract

To advance the capabilities of surface-enhanced Raman scattering (SERS), we developed a silver modi ed polypropylene lter (AgPPF) substrate which acts as a pseudo stationary phase in harvesting SERS signatures of so called "phytochemical estrogens" and other environmentally signi cant chemicals. To augment electron beam lithography (EBL) in SERS research, we also introduced an interesting nanotransfer printing (nTP) technique which could circumvent the low throughput and extremely high resolution (< 10 nm) limitations of EBL in designing advanced SERS substrates.

In our study, a nominal average thickness of 10 nm silver on the polypropylene microfi ber produced nanoglobules of less than 100 nm in diameter. This noble metal nanoroughened layer allowed AgPPF to serve as a SERS active substrate, onto which the noted endocrine disrupting chemicals were passed through and harvested. The intense, multifeatured vibrational Raman spectra of very rarely SERS studied chemical species collected indicates the potential for useful detection via this approach of creating SERS substrates. AgPPF substrates were also used in characterizing the adsorption behavior of hydroxyl complexes of uranium. Interestingly, hydroxyl group on the uranium complexes showed slow sorption kinetics on the nanostructured silver surfaces. Understanding the adsorption behavior of aqueous solution of uranium on nanostructured silver surfaces has opened up the possibilities of SERS detection of these environmental and non-proliferation concerned species without any surface modi cations.

nTP is a high resolution printing technique and relies on interfacial chemistries to control the transfer of thin metal fi lm from a "stamp" to a "substrate". In our research, high-aspect-ratio AutoCAD designed nanopatterns were created on silicon wafers using e-beam lithography and reactive ion etching. Silicon relief pillars based stamps were then used to integrate a variety of nanostructures on diff erent dielectric materials. Thus created nanopatterns have shown their promise to hold their inherent SERS activity. For its simplicity, cost-e ffectiveness, and ease of operation, this hyphenated nTP-SERS technique is impressive in the selection of suitable supporting-fi lms for better SERS enhancements and also to manipulate gap between nanodiscs (gap-plasmonic SERS e ffect).

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