Spectroscopy of AlO: Combined analysis of the A2Πi → X2Σ+ and B2Σ+ → X2Σ+ transitions

A combined analysis of the A(2)Pi(i) -> X-2 Sigma(+) and B-2 Sigma(+) -> X-2 Sigma(+) band systems of AlO, involving 21,500 line assignments, has been performed. The analysis indicates that the previously reported gamma values of the B-2 Sigma(+) state are questionable. The present analysis shows that gamma(B-2 Sigma(+))approximate to 0.014 cm(-1), essentially independent of the vibrational level. The positive sign is consistent with second order interaction with the higher-lying C-2 Pi(r) and lower-lying A(2)Pi(i) states. It also appears that many of the previously reported gamma and gamma(D) values of X-2 Sigma(+) (v > 0) are doubtful. In fact, gamma(X-2 Sigma(+)) is observed to become increasingly negative for v '' > 1, due to second order interaction with the low-lying A(2)Pi(i) state. The present results are based on models where the hyperfine structure of the (2)Sigma(+) states has been taken into account explicitly. Intensity patterns of the branches of the B-2 Sigma(+) -> X-2 Sigma(+) system have been shown to be influenced by the case b beta(s) coupling in the ground state v = 0,1 levels. This gives rise to intensity differences of around 10 percent in the R-1/R-2 and P-1/P-2 doublet components. The synthesized intensity patterns are fully in accord with the F-1/F-2 assignments of the present work. (C) 2010 Elsevier Inc. All rights reserved.