Energy and radiative properties of the low-lying NaRb states - art. no. 052504

Many-body multipartitioning perturbation theory (MPPT) was applied to calcu late the potential energy of 11 lowest electronic states of the NaRb molecu le, A,C-(1)Sigma (+)-X(1)Sigma (+), B,D (1)Pi -X(1)Sigma (+), D (1)Pi -A (1 )Sigma (+) and D (1)Pi -B (1)Pi transition dipole moments, as well as nonad iabatic L-uncoupling matrix elements between the examined (1)Pi and four lo west (1)Sigma (+) states for both (NaRb)-Na-23-Rb-85 and (NaRb)-Na-23-Rb-87 isotopomers. The relevant MPPT ab initio matrix elements and energy curves were converted by means of the approximate sum rule to radiative lifetimes and Lambda -doubling constants (q factors) for the particular rovibronic l evels of the B (1)Pi and D (1)Pi states. The theoretical lifetimes agree we ll with their experimental counterparts for both B (II)-I-1 and D in states . The q factor estimates obtained in the singlet-singlet approximation are in good agreement with the experimental ones for the D (1)Pi (1 less than o r equal tov'less than or equal to 12;7 less than or equal toJ'less than or equal to 50) levels, exhibiting a pronounced difference for the B (1)Pi sta te. Considerably better agreement was achieved by accounting for the spin-o rbit perturbation effect caused by the near-lying c(3)Sigma (+) state. Rela tive intensity distributions in the D (1)Pi-->X (1)Sigma (+) dispersed fluo rescence spectra excited by fixed Ar+ laser lines were measured for v'(J') = 0(44), 1(104), 4(25), 6(44,120), 10(36), and 12(50) D (1)Pi levels. The e xperimental intensities and term values were simultaneously embedded in the nonlinear least-square fitting procedure to refine the D (1)Pi potential.