This article is part of the Journal of Raman Spectroscopy special issue entitled “Development and applications of nonlinear optical spectroscopy -10th ECONOS / 30th ECW meeting in Enschede, The Netherlands” edited by Herman Offerhaus, Peter Radi, and Cees Otto.
Herman–Wallis corrections in dual-pump CARS intensities for combustion temperature and species†
Article first published online: 20 MAR 2012
Copyright © 2012 John Wiley & Sons, Ltd.
Journal of Raman Spectroscopy
Special Issue: Development and applications of nonlinear optical spectroscopy - 10th ECONOS / 30th ECW meeting in Enschede, The Netherlands
Volume 43, Issue 5, pages 595–598, May 2012
How to Cite
Marrocco, M., Magnotti, G. and Cutler, A. D. (2012), Herman–Wallis corrections in dual-pump CARS intensities for combustion temperature and species. J. Raman Spectrosc., 43: 595–598. doi: 10.1002/jrs.3131
- Issue published online: 17 MAY 2012
- Article first published online: 20 MAR 2012
- Manuscript Revised: 9 NOV 2011
- Manuscript Accepted: 9 NOV 2011
- Manuscript Received: 8 NOV 2011
- coherent anti-Stokes Raman scattering;
- laser spectroscopy;
- spectroscopic techniques
Interaction between vibration and rotation in light molecules is responsible for many spectroscopic corrections to the fundamental rigid-rotor model. In this context, we discuss the interpretation of the coherent anti-Stokes Raman scattering (CARS) intensity that is recurrently considered in combustion science to measure high temperatures. Intensity changes are quantified by the Herman–Wallis (HW) factor and, unlike other recent works appearing on the subject where the focus is on thermometry, the present work examines the consequences for the quantitative detection of chemical species. Indeed, the diagnostic potential of CARS spectra is not limited to gas-phase thermometry in that multiple species detection is also possible. To this end, we describe an experiment based on a conventional set-up designed according to the principles of dual-pump CARS that, in our case, allows for the simultaneous measurements of temperatures and mole fractions of nitrogen and oxygen observed in a reference flame operated at equivalence ratios below or near stoichiometry. Two HW factors are compared with common reference to the experimental spectra and the results show that, beyond the confirmation of thermometric corrections of about 0.5% for nitrogen CARS, the choice between different vibrational HW models significantly affects the measurement of mole fractions. The effect reaches 1% for nitrogen at stoichiometric conditions, whereas the sensitivity of oxygen to HW models reaches 2.5%. Copyright © 2012 John Wiley & Sons, Ltd.