Research Support Instruments
Raman Spectroscopy

Identification of Bacteria from Two-Dimensional
Resonant-Raman Spectra

Citation: Analytic Chemistry, ASAP Article 10.1021/ac070681h S0003-2700(07)00681-6


RSI Scientists Charles K. Manka and Sergei Nikitin were prominent contributors to an NRL Plasma Physics research group that first demonstrated  using two-dimensional resonant-Raman spectra to identify  bacteria, including differentiation of genetically similar species.  Developed specificaaly for this purpose, the new device sequentially illuminates bacteria with 200 different ultraviolet wavelengths and measures the spectrum at each.  Information in the two-dimensional spectra should allow identification of bacteria and chemicals in environments containing multiple organisms and chemicals.   This invention, designated swept wavelength optical resonant-Raman device (SWOrRD), may lead to instruments that rapidly identify bacteria in hospital and food plant settings, for screening large populations, and for biochemical-threat warning systems.



Bacterial signatures. Two-dimensional resonant-Raman signatures of E. coli (top row), Y. rohdei and S. epidermidis (middle row), with B. cereus and B. thuringiensis (bottom row). The horizontal axis in each frame is the Raman shift, from 900 to 1800 cm-1, relative to the excitation laser wavelength. The vertical axis is the laser wavelength from 210 to 270 nm. Colors represent the relative amplitude of resonant-Raman scattering from the bacteria.

 

The Plasma Physics Division conducts a broad experimental and theoretical program in basic and applied research in plasma physics, laboratory discharge and space plasmas, intense electron and ion beams and photon sources, atomic physics, pulsed power sources, laser physics, advanced spectral diagnostics, and nonlinear systems.

RSI is under contract to the NRL Plasma Physics Division to provide on-site support to the high energy laser programs including Nike, Electra, and T-cubed.  RSI staff participated in the design and construction of these lasers, their maintenance, and in laser material interaction experiments.  RSI also supports the division’s laser applications experiments, field tests, and diagnostic development efforts.

 

Recent efforts have included participation in the development of a swept Raman spectrometer system for chemical/biological hazard detection, the development of an ultra-fast non-imaging spectrometer for monitoring impact phenomena, and field testing of laser-induced ultrasound diagnostic equipment.

 

Other recent RSI work with the NRL Plasma Physics Division has explored the propagation of continuous-wave high power laser beams through the atmosphere.   RSI personnel supported several field tests, and developed methods to actively sense beam power, position and size.  A current interest of the group is to investigate whether Yb-Fiber lasers can be used to remotely power UAVs through power beaming.  Like laser communication, the group is studying the effects of atmospheric turbulence and scattering from aerosols. 


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