Final Report: Investigation of Saturated Degenerate Four-Wave Mixing Spectroscopy For Quantitative Concentration Measurements

Our research efforts over the last few years have focused on the development of strategies for the quantitative application of DFWM and PS in flame environments. We have developed, validated, and applied a theoretical methodology based on direct numerical integration (DNI) of the time-dependent density matrix equations for analysis of the physics of the DFWM and PS processes. The incorporation of the Zeeman state structure of the energy levels of the radiative transitions has allowed us to investigate the physics of the PS process and polarization effects in DFWM. Our research effort has focused mainly on the moderate saturation regime, with laser pulse lengths significantly greater than characteristic collisional times, and with the assumption of monochromatic lasers. Recently, we have completed a study of multi-axial-mode laser effects of homogeneously broadened PS