The transitions between Ar * 2 (5p) and Ar * 2 (4sΣ u ) have been investigated by absorption spectrometry. The fine structure of the Ar * 2 (5p 3 Π g ) was attributed to a predominantly Hund's case a coupling. A spin orbit coupling constant of A = (9.8±0.3) cm −1 results. Absorption by the singlet system allows one to determine the triplet/singlet splitting between the Ar * 2 (4sΣ u ) states to be (540 ± 100) cm −1 . The transition probabilities of the Ar * 2 (5p) and Ar * 2 (6p) levels were determined by saturation spectrometry yielding values between (0.2 − 2.5) · 10 6 s −1 .