Flame Diagnostics

Possible applications of laser enhanced ionization in flame diagnostics are 1. simultaneous observation of ionization and fluorescence signals from various levels might provide more information on the sequence of processes leading to and from the ionization continuum 2. the measurement of ion mobilities, relating to cross-sections for elastic collisions between ions and flame particles 3. measurement of ionization rate constants relating to cross-sections for inelastic collisions between excited atoms and other flame particles 4. measurement of recombination rate constants, relating to cross-sections for inelastic collisions between ions, electrons and neutrals. 

These include temperature, major constituent densities, gas velocity, and correlations of these properties. We discuss here the advantages and limitations of various potential light-scattering probes, and illustrate these with recent results for vibrational Raman scattering flame diagnostics. 

The fundamentals of the Raman effect can be understood by consideration of a classical model, in which an incident beam of radiation (i.e., laser beam, for all practical purposes, in flame diagnostics) passes through an ensemble of molecules. The resultant laser beam electric field distorts the electronic cloud distribution of each molecule, causing oscillating dipoles these induced dipoles are related to the incident laser beam electric field by the molecular polarizability. The dipoles, in turn, produce a secondary radiating field at essentially the same frequency as that for the incident beam. This radiation is termed Rayleigh scattering. 

Taran, J.P., "CARS Flame Diagnostics" presented at the CARS meeting of the Institute of Physics, AERE Harwell, March 1979. 

The application of LEI spectrometry to flame diagnostics has been recently reviewed 51). This is a research area where the unique aspects of the technique can provide some new insights into combustion systems. 

V. Hefter, K. Bergmann, Spectroscopic detection methods, in Atomic and Molecular Beam Methods, vol. 1, ed. by G. Scoles (Oxford Univ. Press, New York, 1988), p. 193 J.E.M. Goldsmith, Recent advances in flame diagnostics using fluorescence and ionisation techniques, in Laser Spectroscopy VIII, ed. by S. Svanbeig, W. Persson. Springer Ser. Opt. Sci., vol. 55 (Springer, Berlin, 1987), p. 337... 

J.E.M. Goldsmith Recent advances in flame diagnostics using fluorescence and ionization techniques, in [Ref.9.26, p.337]... 

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