This proposal describes an integrated research, education and outreach plan with a focus on plasmonic nanocavities and their applications in single molecule surface enhanced Raman spectroscopy (SERS). The proposed plasmonic nanocavities, or the tiny gaps between metal nanowires (Ag), are formed by stacking a second layer of parallel Ag nanowires on top of a first layer of perpendicularly oriented Ag nanowires. Preliminary studies show that when the gaps between top and bottom nanowires are reduced to a few nanometers or ten millionth of the diameter of a human hair, illuminating light can be focused into such tiny nanogaps with up to 100000 times increase in light intensity. When molecules are placed inside these plasmonic nanocavities, their Raman scattering intensity can be largely enhanced so that even single molecule signals can be observed. The Raman spectra represent unique vibration information of molecules which can be used for direct detection and identification of the molecules. The proposed research aims at developing nanofabrication processes for nanowires and nanocavities, characterization and fundamental understanding of these plasmonic nanocavities, and exploring their applications in SERS. The ultimate goal is to demonstrate a robust single molecule sensing platform based on SERS. The education plan includes implementing an educational program aimed to attract high ability students in Northeast Ohio to majors in STEM (science, technology, engineering and mathematics) fields and to provide those students already in STEM fields with mentoring and research opportunities.
Intellectual merit: The Ag nanowire crossbars are unique in three aspects: (1) nanoantennas (i.e. Ag nanowire) and nanocavities are integrated in single platform, making it highly efficient to focus light into nanometer scale; (2) the vertical cavity design makes it possible to fabricate nanogaps with unprecedented accuracy by using thin film deposition techniques; (3) Molecules within these nanocavities can be addressed electrically by applying voltages through these nanowires, providing great flexibility to control the molecules and nanocavities. The proposed research will answer fundamental questions about SERS enhancement mechanisms and lead to development of reproducible single molecule sensors.
Broader impact: The proposed research benefits society because single molecule sensors can find myriad applications from homeland security to disease diagnostics for healthcare. The educational and outreach components of this career plan include developing of a guided research experience program for the Post Secondary Enrollment Option Program (PSEOP) students at Kent State University (KSU); mentoring undergraduates in research; creating an outreach program called ?Parent?s Night? for high school students and their parents; enhancing graduate education through involving graduate students in multidisciplinary research, and developing curriculum for teaching nano/biomaterials at the graduate level. KSU is one of three largest public universities in the state of Ohio, over 80% KSU students are undergraduates; and KSU primarily serves low- to middle-income undergraduates. This unusual combination of institutional traits makes KSU ideally suited to recruit students from under-represented groups and/or disadvantaged communities to pursue careers in science and related fields. The proposed educational plan will have a direct impact on improving enrollment, retention, and graduation rates of under-represented group members and women in science and related fields at KSU.
