CARS in combustion: Prospects and problems

Review of temperature measurement

“…As the signal appears on the high frequency side of the pump, i.e., an anti-Stokes spectrum, and because it is observable only if the molecular vibrations are Raman active, this generation mechanism is called coherent antiStokes Raman scattering. 155 CARS permits noninvasive local temperature measurement in gases, flames, or plasmas. 156 Since temperature is related to the rotational state of the molecules, the anti-Stokes lines increase in intensity with increasing temperature.…”

Pressure Broadening, Shift, and Interference Effect for a Multiplet Line in the Rovibrational Anisotropic Stimulated Raman Spectrum of Molecular Oxygen

“…The absolute frequency represents the average unperturbed frequencies deduced from the observed frequencies where r j is the population density at thermodynamic equilibby subtracting the collisional shift determined at higher presrium and a j the matrix element of the anisotropic polarizabilsure. The absolute frequencies obtained in this work are in ity a (2) for the j transition. very good agreement with those determined by Rouillé et Equation [6] can also be written as al.…”

“…In the Q Q branch the triplet It has been demonstrated within these last years that coherent structure is usually not resolved because of the extremely small anti-Stokes Raman spectroscopy (CARS) is a versatile tool differences between the transition frequencies. However, in a for temperature and concentration measurements in various few particular cases, where a large pulse duration (10) or a gaseous media (1,2). Among the probe molecules used, oxygen molecular free-expansion jet (11) is used, the Q Q(J, N) triplets has been involved by CARS spectroscopy in many practical can be partially resolved for N £ 3.…”

Atomic oxygen detection using two-photon degenerate four wave mixing

“…However, line intensities and linewidths may differ substantially in nonlinear and in linear spectra [20]. The most important differences stem from: (i) the effect of collisional quenching that mainly affects the LIF signal yield, separate lifetime measurements are necessary [25]; (ii) the geometrical factors specific to nonlinear excitation using co-or crossed-polarized exciting fields [32,33]; (iii) the narrower linewidth obtained in some resonant nonlinear spectroscopy [34]. The spectral positions of the components of the oxygen triplet from J"2 are given in Table 1 together with the positions of nearby NO lines of the system.…”

“…The data are simulated (solid line) using the perturbative theory [18,20,34]. The collisional broadening coefficients are drawn from Chang et al [37].…”