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Abstract: A combined analysis of the A 2Πi → X 2Σ+ and B 2Σ+ → X 2Σ+ band systems of AlO, involving 21,500 line assignments, has been performed. The analysis indicates that the previously reported γ values of the B 2Σ+ state are questionable. The present analysis shows that γ(B 2Σ+)≈0.014cm−1, essentially independent of the vibrational level. The positive sign is consistent with second order interaction with the higher-lying C 2Πr and lower-lying A 2Πi states. It also appears that many of the previously reported γ and γ D values of X 2Σ+ (v >0) are doubtful. In fact, γ(X 2Σ+) is observed to become increasingly negative for v″>1, due to second order interaction with the low-lying A 2Πi state. The present results are based on models where the hyperfine structure of the 2Σ+ states has been taken into account explicitly. Intensity patterns of the branches of the B 2Σ+ → X 2Σ+ system have been shown to be influenced by the case bβ 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. [ABSTRACT FROM AUTHOR]

Abstract: A time-resolved experiment on the A 2 Π state of gaseous calcium hydride has been performed by applying laser spectroscopic methods. The following zero-pressure lifetime was obtained for the CaH A 2 Π state: τ υ´=0 =33.2 (±3.2) ns and τ υ´=1 =33.7 (±5.2) ns. The lifetime was found to be the same for the A 2 Π ½ and A 2 Π 3/2 states. [Copyright &y& Elsevier]