Electronic spectroscopy of the Al+–Ar complex

The laser fluorescence excitation spectrum of the Al+–Ar complex near the Al+ ion 3s3p 1P ← 3s2 1S resonance transition is reported. An excited-state (v′, 0) progression and the (0, 1) hot band were observed. Rotational analysis revealed that these bands involve an electronic transition from the Al+–Ar X 1Σ+ ground state to the 1Σ+ state correlating with the Al+(1P)+Ar asymptote. Rotational constants and upper-state vibrational constants and the dissociation energy were determined. The spectroscopic constants of the two observed Al+–Ar electronic states are compared with those for neutral AlAr states.