Table 1: List of the 15 lower energy levels of Ar I.

c/c l jK LS P.N. E. exp. Char. 1 3p 3 1 1S0 0 1 0.000 2 4s 4 0 [3/2]2 3P2 1s5 2 5 93143.7600 m 3 4s 4 0 [3/2]1 3P1* 1s4 1 3 93750.5978 t 4 4 0 [1/2]0 3P0 1s′3 0 1 94553.6652 m 5 4 0 [1/2]1 1P1* 1s′2 1 3 95399.8276 t 6 4p 4 1 [1/2]1 3S1 2p10 1 3 104102.0990 q-m 7 4p 4 1 [5/2]3 3D3 2p9 3 7 105462.7596 q-m 8 4p 4 1 [5/2]2 3D2 2p8 2 5 105617.2700 9 4p 4 1 [3/2]1 3D1 2p7 1 3 106087.2598 10 4p 4 1 [3/2]2 3P2 2p6 2 5 106237.5518 q-m 11 4p 4 1 [1/2]0 3P0∘ 2p5 0 1 107054.2720 12 4 1 [3/2]1 1P1 2p′4 1 3 107131.7086 13 4 1 [3/2]2 1D2 2p′3 2 5 107289.7001 14 4 1 [1/2]1 3P1 2p′2 1 3 107496.4166 15 4 1 [1/2]0 1S0∘ 2p′1 0 1 108722.6194

: level index. c/c: configuration and core description. description from NIST, LS description from our CbA calculations. Unprimed for core 2P3/2, primed for core 2P1/2. Symbols *, , ° denote the most strongly mixed levels; all the levels with the same within a same configuration are mixed. P.N.: Paschen notation. E. exp.: experimental energy from NIST in cm−1. Char.: character of the level: transitory/metastable/quasimetastable.