The c (3)Sigma(+), b (3)Pi, and a (3)Sigma(+) states of NaK revisited

We present new c (3)Sigma(+)--> a (3)Sigma(+) laser induced fluorescence sp ectra of the NaK molecule, which clearly indicate that v(0) = 20 is the fir st vibrational level of the c (3)Sigma(+) state lying above v = 0 of B (1)P i state. These spectra are used in a multistep deperturbation (B (1)Pi simi lar to c (3)Sigma(+) similar to b (3)Pi) procedure to obtain improved a (3) Sigma(+), b (3)Pi and c (3)Sigma(+) potential energy curves. The deperturba tion analysis is confirmed by the calculated electronic B (1)Pi similar to c (3)Sigma(+) and c (3)Sigma(+) similar to b (3)Pi spin-orbit matrix elemen ts obtained from many-body multipartitioning perturbation theory employing the relativistic effective potential method. (C) 2000 American Institute of Physics. [S0021-9606(00)00213-0].