A revised analysis of the spectrum of Ar III

A revised and extended analysis of the optical spectrum of Ar III is presented. All the energy levels in the 3s 2 3p 4 , 3s3p 5 , 3s 0 3p 6 , 3s 2 3p 3 4s, 4p and 3d configurations are reported. Nearly all the singlet terms, which are of particular interest in Auger spectroscopy are new. An interpretation of the odd configurations based on a newly introduced orthogonal parameter set for p N d configurations is reported. The strong mixing between parent terms in the 3p 3 3d configuration is noted and some consequences for the spectroscopy of Ar n+ +Ar collisions are discussed. A comparison with Auger results for the LMM transitions in Ar is given.