DEGENERATE 4-WAVE-MIXING SPECTROSCOPY IN NAH

We performed DFWM spectroscopy on X1 SIGMA+-A1 SIGMA+ transitions in N aH produced in an indirect photochemical reaction between Na(3p) and H -2 and detected upsilon'' = 1,2 and 3 ground state vibrational levels of NaH molecules, whereas with resonance enhanced CARS, we observed up silon'' = 0 levels only. This different sensitivity can be explained b y considering the Franck-Condon-factors and the relevant damping coeff icients for the corresponding transitions in the NaH molecule. Time re solved DFWM spectroscopy showed that NaH(upsilon'' = 1) molecules effe ctively live much longer than Na(3p) atoms which merely follow the las er excitation pulse.