We present the first measurements of two-dimensional resonant-Raman spectra and demonstrate the applicability of the method to the identification of bacteria, including differentiation of genetically similar species. A new device that sequentially illuminates bacteria with different ultraviolet wavelengths and measures a spectrum at each was developed for this purpose. We anticipate that information within such two-dimensional spectra will allow identification of bacteria and chemicals in environments containing multiple organisms and chemicals, leading, for example, to instruments that rapidly identify bacteria in hospital and food plant settings, for screening large populations, and for biochemical-threat warning systems.

The first two-dimensional (2D) resonance Raman spectra of TNT, RDX, HMX, and PETN are measured with an instrument that sequentially and rapidly switches between laser wavelengths, illuminating these explosives with forty wavelengths between 210 nm and 280 nm. Two-dimensional spectra reflect variations in resonance Raman scatter with illumination wavelength, adding information not available from single or few one-dimensional spectra, thereby increasing the number of variables available for use in identification, which is especially useful in environments with contaminants and interferents. We have recently shown that 2D resonance Raman spectra can identify bacteria. Thus, a single device that identifies the presence of explosives, bacteria, and other chemicals in complex backgrounds may be feasible.

No abstract

No abstract