* A. V. STOLYAROV*, V. I. PUPYSHEV, E. A. PAZYUK, A. ZAITSEVSKII, DEPARTMENT OF CHEMISTRY, MOSCOW STATE UNIVERSITY, GSP-2 LENINSKIE GORY 1/3, MOSCOW 119992, RUSSIA; O. DOCENKO, M. TAMANIS, R. FERBER, DEPARTMENT OF PHYSICS AND INSTITUTE OF ATOMIC PHYSICS AND SPECTROSCOPY, UNIVERSITY OF LATVIA, 19 RAINIS BOULEVARD, RIGA LV-1586, LATVIA; A. PASHOV, DEPARTMENT OF PHYSICS, SOFIA UNIVERSITY, 5 JAMES BOURCHIER BLVD, 1164 SOFIA, BULGARIA; H. KNÖCKEL, E. TIEMANN, INSTITUT FÜR QUANTENOPTIK, GOTTFRIED WILHELM LEIBNIZ UNIVERSITÄT HANNOVER, WELFENGARTEN 1, 30167 HANNOVER, GERMANY.

\noindent The direct deperturbation analysis of the singlet-triplet A^{1}
^{+}
b^{3}
complex of Na^{85}Rb and Na^{87}Rb isotopomers was performed in the framework of the inverted channel-coupling approach . Besides of Born-Oppenheimer potential energy curves of the mutually perturbed states and the off-diagonal spin-orbit (SO) A
b coupling function, the SO splitting of the b^{3}
state was determined due to the pronounced electronic- rotation interaction between the b^{3}
_{0} and b^{3}
_{1} components observed for high J-levels. Overall 24 mass-invariant fitting parameters have been required to reproduce about 2300 experimental term values of both isotopomers with a standard deviation of 0.012 cm^{-1} which is consistent with the uncertainty of the Fourier transform spectra measurement. The experimental relative intensities in the D^{1}
\to A
b spectra highlighted the breakdown of the conventional oscillation theorem. The strong intensity borrowing effect caused by the SO coupling and enhanced by the violation of the Franck-Condon principle was analyzed. The calculated A
b - a, X transition probabilities were applied for simulation of the stimulated Raman processes a^{3}
^{+} \to A
b \to X^{1}
^{+} which can lead to efficient formation of ultracold NaRb molecules in the ground level v_{X}=0;J_{X}=0. The quantitative transition moments predicted for favorable lambda schemes show that such experiments are feasible.