Improved Sensing Using Simultaneous Deep UV Raman and Fluorescence Detection

This proposal addresses the need to increase the probability of detection (PD) and reduce the probability of false alarm (PFa) for non-contact, real-time sensors for trace levels of biological and chemical targets using simultaneous detection of Raman and fluorescence emissions. Raman spectroscopy is a spectroscopic method that provides information about molecular bonds in target materials. Fluorescence spectroscopy is a much more sensitive spectroscopic method that provides information regarding the electronic configuration of target molecules. Photon Systems has been developing combined Raman and fluorescence methods for over 6 years with a focus on the advantages of excitation in the deep UV below 250nm. There are three main advantages of excitation in the deep UV, below 250nm compared to near-UV, visible or near-IR counterparts. 1) Raman scattering occurs in a fluorescence-free region of the spectrum. At longer excitation wavelengths, fluorescence from target or surrounding materials overwhelm weak Raman emissions, making them impossible to detect. 2) The wavelength range for Raman and fluorescence emissions is separate, enabling simultaneous detection of both modes of emission. 3) Resonance Raman occurs for a wide range of biological and organic materials, providing simplified and more easily interpreted Raman spectra as well as enabling enhanced Raman signal strength.