An Analysis of Coherent Anti-Stokes Raman Spectroscopy as an Analytical Tool
NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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Coherent Anti-Stokes Raman Spectroscopy CARS is a new type of Raman Spectroscopy. The phenomenon is associated with the nonlinear conversion of two laser beams in a medium into a third collimated beam at the anti-Stokes frequency of the medium. This analysis evaluates the performance capabilities of CARS under various experimental conditions for the molecules O2,N2,H2 and CO. Laser intensity fluctuations and shot noise are introduced as noise sources to predict signal-to-noise ratios SN. The SN is evaluated as a function of the partial pressure of a gas to measure the performance of CARS. An analysis of the uncertainty in measuring the rotational temperature is presented for diatomic gases. Inverse bremsstrahlung in plasmas is investigated as a possible process by which the parameters measured by CARS might be altered. An experiment is discussed in which an attempt was made to remove the background signal inherent in most CARS experiments. Partial interferometric cancellation of two CARS signals was observed by the proper positioning of two sample cells in an otherwise standard CARS experiment.
- Atomic and Molecular Physics and Spectroscopy