Ultra-Sensitive Raman Detector:A SERS Spectrometer

Surface-enhanced Raman scattering (SERS) for handheld, field analysis of biological health and safety threats requires the development of an advanced, compact Raman spectrometer tailored to SERS. Our proposed efforts will decrease spectrometer size, lowerits power consumption, expand the Raman spectral range and develop an optical interface that improves excitation and collection efficiency when compared to current portable Raman systems. A novel spectrometer design based solely on fiber optics technologywill be built in a fraction of the volume possible with dispersive instruments as a means of achieving the goal of handheld operation. This spectrometer will be coupled to our highly sensitive SERS sensors through specially designed and tested opticalinterfaces that account for the angular and spatial dependence of the excitation phenomenon. Analyte will be delivered to the substrate through sample collection mechanisms that account for the aerodynamics and thermodynamics that dictate SERSsubstrate/analyte interactions. The design features of the proposed SERS spectrometer based biological sensor will be thoroughly tested in a research program organized around understanding optimal SERS excitation, collection, and substrate analyteinteractions. The research will also be directed at increasing excitation efficiency through the use of microcavities. Small and inexpensive Raman instrumentation will bring new commercial applications of the method, including quality control analysis,process controllers, forensic instruments for identifying illegal substances, and air and water monitors.