NEW DUNHAM COEFFICIENTS OF THE A(1)SIGMA(-STATE OF NAH AND NAD())

We determined new Dunham coefficients of the A(1) Sigma(+)-State of Na H and NaD from degenerate Four-Wave-Mixing (DFWM) spectra in the near UV and in the blue spectral region. In the case of NaH we combined the se data with results of Rafi et al. and Orth et al.. The new set of co efficients describes the vibrational dependence of the rotational cons tants B and D and of the band origins from upsilon' = 0 up to 25. The spectral positions of the lines in our DFWM-spectra can be reproduced by this coefficients with an accuracy better than 0.3 cm(-1) for J-val ues less than or equal to 15 and 2 cm(-1) for J-values less than or eq ual to 25. Especially for high J-values this is an improvement up to 3 0 times in comparison to Dunham coefficients recommended before. A RKR -potential of the A(1) Sigma(+)-state was calculated with the new coef ficients. The Dunham coefficients of NaD were obtained by scaling the NaH coefficients with the reduced masses of the molecules. A compariso n of our results to molecular constants determined from the measured N aD-spectra shows good agreement.