Theory of femtosecond coherent anti-Stokes Raman backscattering enhanced by quantum coherence for standoff detection of bacterial spores

Ooi, Chong Heng Raymond and Scully, M.O. and Beadie, G. and Kattawar, G.W. and Reintjes, J.F. and Rostovtsev, Y. and Zubairy, M.S. (2005) Theory of femtosecond coherent anti-Stokes Raman backscattering enhanced by quantum coherence for standoff detection of bacterial spores. Physical Review A, 72 (2). ISSN 1050-2947, DOI https://doi.org/10.1103/PhysRevA.72.023807.

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Abstract

Backscattered signal of coherent anti-Stokes Raman spectroscopy can be an extremely useful tool for remote identification of airborne particles, provided the signal is sufficiently large. We formulate a semiclassical theory of nonlinear scattering to estimate the number of detectable photons from a bacterial spore at a distance. For the first time, the theory incorporates enhanced quantum coherence via femtosecond pulses and a nonlinear process into the classical scattering problem. Our result shows a large backscattered signal in the far field, using typical parameters of an anthrax spore with maximally prepared vibrational coherence. Using train pulses of 1 kHz of repetition rate each with energy of 10 mJ, we estimate that about 10(7) photons can be detected by a 1 m diameter detector placed 1 km away from the spore in the backward scattering direction. The result shows the feasibility of developing a real time remote detection of hazardous microparticles in the atmosphere, particularly biopathogenic spores.

Item Type:	Article
Funders:	UNSPECIFIED
Additional Information:	Department of Physics, Faculty of Science Building, University of Malaya, 50603 Kuala Lumpur, MALAYSIA
Uncontrolled Keywords:	Nonlinear frequency-conversion; Dipicolinic acid; Light-pulses; Laser-pulses; Fast cars; Generation; Scattering; Spectroscopy; Propagation; Dynamics
Subjects:	Q Science > QC Physics
Divisions:	Faculty of Science > Department of Physics
Depositing User:	Miss Malisa Diana
Date Deposited:	08 Jul 2013 08:44
Last Modified:	09 Oct 2019 00:46
URI:	http://eprints.um.edu.my/id/eprint/7929

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