Improved formulae for the intensity profile of the rotational lines have been derived for the [ndσΣ+, ndπII, ndδΔ] (Hund's case d)-n'pπII (case b) electronic bands of diatomic molecules with respect to the l-uncoupling interaction among the upper states. As an application of the formulae, the rotational temperature in the dc discharge plasma was determined from the analysis of the band structure of the He2[3dσf3Σ+u, 3dπf3IIu, 3dδf3Δu] ← 2pπb3IIg (0-0) absorption bands. The formulae were also applied to the H2 [3dσg3Σ+u, 3dπi3IIu, 3dδj3Δu] → 2pπc3IIg (0-0) emission bands.
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