Rotational line strengths in degenerate four wave mixing

Atomic oxygen detection using two-photon degenerate four wave mixing

“…The pump beam P is vertically polarized whereas the P pump and the probe beam Pr are horizontally polarized. This arrangement was demonstrated to provide optimal signal to noise ratio in forward DFWM involving one-photon resonances [18,20]. The three parallel beams are focused at the probe volume using a 400 mm focal length lens for most of the study.…”

“…The Doppler and laser bandwidth are taken into account as usual [20,34]. The simulation also takes into account the Ho¨ln-London and geometrical factors in the susceptibility numerator [20,21,32,33]. These geometrical factors are calculated in the crossed-polarization case depicted in Three interesting results are drawn from the fitting of spectra in Fig.…”

“…DFWM spectroscopy is known to be identical to linear spectroscopy as far as line positions are concerned [31]. 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 collisional broadening coefficients are drawn from Chang et al [37]. The Doppler and laser bandwidth are taken into account as usual [20,34]. The simulation also takes into account the Ho¨ln-London and geometrical factors in the susceptibility numerator [20,21,32,33].…”

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