Article révisé par les pairs
Résumé : We have used continuous-wave cavity ring-down spectroscopy to record a band with origin close to 7275.1 cm-1 in an Ar supersonic expansion seeded with H2O. It is assigned to ν1 + ν3 ← GS, Π(101) ← Σ(000) in Ar-H2O. The rotational structure (Trot = 12 K) is analyzed and the lines fitted (σ = 0.0008 cm-1) together with literature microwave data. The fit includes strongly perturbed Q lines, from interaction with a Π state with origin determined to be close to 7274.5 cm-1. The mean upper state predissociation lifetime is determined to be 3 ns for all reported e and f upper levels.