Rotational and vibrational temperature determination by DFWM spectroscopy

Using the DFWM technique we determined rotational and vibrational temperatures of NaH molecules in a dynamical system consisting of NaH, Na, H and H₂ for several heat-pipe oven temperatures. We applied a new way to determine the dependence of the DFWM signalI_c^int on the power of the transition dipole momentµ without previous knowledge of the temperature. The revealed dependence isI_c^intµ⁴. In this case the laser intensities were found to be of the same order as the saturation intensity in accordance with simple DFWM theory. A usual Boltzmann plot was employed for the determination of the relevant rotational temperatures, which displayed higher values than the oven temperature.