Constants of the second 0 g+ ion-pair state of I 2

The second 0 _g⁺ ion-pair state of I ₂ is characterized using two-stage polarization-labeling spectroscopy. Molecular constants for this state in the range 0 ≤ v ≤ 25, based on a global leastsquares fit of 450 transitions, are (in cm ^-1) T_e = 47 025.917, ω_e = 104.1804, ω_ex_e = 0.21324, ω_ey_e = 2.46 × 10 ^-4, B_e = 2.08042 × 10 ^-2, α_e = 5.728 × 10 ^-5, γ_e = 5.8 × 10 ^-8, and D_e = 3.32 × 10 ^-9. The diabatic potential curve correlates with the states I^-( ¹S) + I⁺( ³P ₀) of the separated ions.