Validation of a rotational coherent anti-Stokes Raman spectroscopy model for carbon dioxide using high-resolution detection in the temperature range 294-1143 K

Abstract

Experiments were performed in the temperature range of 294-1143 K in pure CO(2) using high-resolution rotational coherent anti-Stokes Raman spectroscopy (CARS), in the dual-broadband approach. Experimental single-shot spectra were recorded with high spectral resolution using a single-mode Nd:YAG laser and a relay imaging lens system on the exit of a 1 m spectrometer. A theoretical rotational CARS model for CO(2) was developed for evaluation of the experimental spectra. The evaluated mean temperatures of the recorded single-shot dual-broadband rotational coherent anti-Stokes Raman spectroscopy (DB-RCARS) spectra using this model showed good agreement with thermocouple temperatures, and the relative standard deviation of evaluated single-shot temperatures was generally 2-3%. Simultaneous thermometry and relative CO(2)/N(2)-concentration measurements were demonstrated in the product gas of premixed laminar CO/air flames at atmospheric pressure. Although the model proved to be accurate for thermometry up to 1143 K, limitations were observed at flame temperatures where temperatures were overestimated and relative CO(2)/N(2) concentrations were underestimated. Potential sources for these discrepancies are discussed.

Single-shot gas-phase thermometry using pure-rotational hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering

“…where b J,J + 2 is the Placzek-Teller coefficient representing the overlap integral of the upper and lower energy state wavefunctions, γ' is the polarization anisotropy, and F(J) is a correction term for centrifugal distortion [34]. This correction for vibrational-rotational interaction is the so-called Herman-Wallis factor [35] and is defined in the current model using the formulation of Martinsson as shown in Eq.…”

Validation of a rotational coherent anti‐Stokes Raman scattering model for N2O at temperatures from 295 K to 796 K

“…The implementation of N 2 O was accomplished utilizing a generic structure from a previous theoretical rotational CARS code for CO 2 , which is based on a main frame described in . The procedure of the present work is very much inspired by the guidelines given in and follows many of the approximations made therein.…”

“…Thus, theoretical models are relatively straightforward to implement, and such models have been built for several molecules of combustion interest; N 2 , O 2 , and CO . Some successful attempts have also been made for symmetric tri‐atomic and four‐atomic molecules: CO 2 and C 2 H 2 . Another approach of coherent anti‐Stokes Raman spectroscopy is vibrational CARS, which has also been used to study diatomics and triatomics, in fact also N 2 O …”

High temperature O2 vibrational CARS thermometry applied to a turbulent oxy‐fuel combustion process

“…[31,32] In all of these applications, the N 2 molecule is used as a temperature indicator. However, also other molecules, like O 2, [33,34] CO 2, [35,36] CO, [37,38] H 2 [39,40] and H 2 O, [41,42] have been used successfully as a temperature indicator.…”