CARS spectral fitting with multiple resonant species using sparse libraries
Article first published online: 6 APR 2011
Copyright © 2011 John Wiley & Sons, Ltd.
Journal of Raman Spectroscopy
Volume 42, Issue 11, pages 1949–1957, 15 November 2011
How to Cite
Cutler, A. D. and Magnotti, G. (2011), CARS spectral fitting with multiple resonant species using sparse libraries. J. Raman Spectrosc., 42: 1949–1957. doi: 10.1002/jrs.2948
- Issue published online: 10 NOV 2011
- Article first published online: 6 APR 2011
- Manuscript Accepted: 16 FEB 2011
- Manuscript Received: 3 MAR 2010
- dual-pump CARS;
The coherent anti-Stokes Raman spectroscopy (CARS) technique is often used in the study of turbulent flames. Fast and accurate algorithms are needed for fitting CARS spectra for temperature and multiple chemical species. This paper describes the development of such an algorithm. The algorithm employs sparse libraries whose size grows more slowly with number of species than a regular library. It was demonstrated by fitting synthetic ‘experimental’ dual-pump CARS spectra containing four resonant species (N2, O2, H2 and CO2), both with added noise and without it, and by fitting experimental spectra from a H2air flat flame produced by a Hencken burner. In the four-species example, the library was nearly an order of magnitude smaller than the equivalent regular library (fitting times are correspondingly faster), and the fitting errors in the absence of added noise were negligible compared to the random errors associated with fitting noisy spectra. When fitting noisy spectra, weighted least squares fitting to signal intensity, as opposed to least squares fitting or least squares fitting to square root of intensity, minimized random and bias errors in fit parameters. Copyright © 2011 John Wiley & Sons, Ltd.