Perturbative theory and modeling of electronic-resonance-enhanced coherent anti-Stokes Raman scattering spectroscopy of nitric oxide

Abstract

for ERE-CARS NO spectra has been developed in the perturbative limit. Comparisons to experimental spectra are presented where either the probe laser was scanned with fixed Stokes frequency or the Stokes laser was scanned with fixed probe frequency. At atmospheric pressure and an NO concentration of 100 ppm, good agreement is found between theoretical and experimental spectral peak locations and relative intensities for both types of spectra.Factors relating to saturation in the experiments are discussed, including implications for the theoretical predictions.

Laser diagnostics and minor species detection in combustion using resonant four-wave mixing

“…OH radicals were also involved in several works where resonantly enhanced CARS was compared to DFWM [60,145] However, more recently, the interest in using CARS for intermediate and minor species detection has experienced a kind of renaissance. In particular the dual-pump CARS approach illustrated in figure 5.2b where the probe laser wavelength is tuned to an electronic transition of the species under investigation was employed to study nitric oxide [132,[156][157][158][159] and acetylene [160]. This approach has some advantages compared to the one with three lasers in [161] studied collisional effects on the molecular dynamics and made a comparison with a previous investigation on quenching of NO in the presence of CO 2 , O 2 and N 2 [162].…”

“…As mentioned before, the probability of such two-photon excitation is much lower than one-photon processes and consequently the sensitivity of the Raman process allows only major species to be detected with a minimum concentration of typically ~1%. In order to increase the sensitivity to allow minor species detection (~100 ppm) the probe laser may be tuned to an allowed electronic transition (see figure 5.2b) [132]. By taking this resonance enhancement one step further tuning all laser frequencies to electronic transitions of the molecule of interest, as illustrated in figure 5.2c, detection limits of the order of 1 ppm can be achieved [16].…”

“…In particular the dual-pump CARS approach illustrated in figure 5.2b where the probe laser wavelength is tuned to an electronic transition of the species under investigation was employed to study nitric oxide [132,[156][157][158][159] and acetylene [160]. This approach has some advantages compared to the one with three lasers in As mentioned above the NO molecule has been extensively studied in recent years.…”

“…A perturbative theory (i.e. for low input laser powers) and a model for calculating ERE-CARS spectra of NO was then developed [132]. In order to validate the model Kuehner et al…”

Tracking molecular wave packets in cesium dimers by coherent Raman scattering

“…Coherent optical response in gas has been revealed by using the Fourier transform of two-dimensional spectroscopic measurements [21,22]. A time-dependent perturbation theory has been adopted to understand various FWM processes [23][24][25]. Density matrix formalism [26] has proved to be an important tool to interpret molecular coherent processes observed in femtosecond experiments [27,28].…”