Premium
On the sensitivity of rotational O 2 CARS thermometry to the Herman–Wallis factor
Author(s) -
Bohlin Alexis,
Nordström Emil,
Bengtsson PerErik,
Marrocco Michele
Publication year - 2012
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.3147
Subject(s) - raman spectroscopy , chemistry , oxygen , rotation (mathematics) , anisotropy , nitrogen , line (geometry) , rotational speed , raman scattering , spectral line , dimension (graph theory) , field (mathematics) , analytical chemistry (journal) , atomic physics , nuclear magnetic resonance , optics , physics , quantum mechanics , geometry , mathematics , organic chemistry , pure mathematics
Contributions of vibration–rotation interaction to line intensities of pure rotational coherent anti‐Stokes Raman scattering (CARS) of oxygen are here considered in the perspective of what was remarked by us recently for nitrogen. The interaction is conventionally evaluated by means of the so‐called Herman–Wallis (HW) factor, the need of which is conceptually clear but the theoretical expression is debatable, as shown in the literature of this field. In this work, the various solutions for the anisotropic HW factor of pure rotational Raman transitions are compared in light of the implications for the corresponding CARS spectral line intensities. The results show that neglecting the use of HW factors in rotational N 2 and O 2 CARS thermometry leads to systematic overestimation of temperatures; on the order of 1.5% in the temperature range 300–2100 K in comparison with the use of the most plausible HW factors. The results also suggest that, in general, oxygen is more sensitive than nitrogen to the HW correction, and in particular, different S‐branch HW expressions for oxygen are responsible for thermometric uncertainties between 0.5% and 1% at flame temperatures. Copyright © 2012 John Wiley & Sons, Ltd.