The ArI2(ion-pair states) van der Waals complexes

Highlights: • The ${\text{ArI}}_2\left(E{0}_{\text{g}}^{+}\right)$ van der Waals complexes have been observed and studied for the first time. • Luminescence spectra of the complex predissociation products have been measured. • The dominant decay channel of ArI₂(E) complexes is electronic predissociation. • Spectroscopic parameters of the ArI₂(E) state have been determined. The ${\text{ArI}}_2\left(E{0}_{\text{g}}^{+}\right)$ van der Waals complexes have been observed and studied for the first time. Analysis of the luminescence excitation spectra as well as luminescence spectra themselves in the spectral ranges, where the ${\text{I}}_2(E{0}_{\text{g}}^{+}\to B{0}_{\text{u}}^{+}\text{,}$ $D{0}_{\text{u}}^{+}\to X{0}_{\text{g}}^{+}\text{,}$ β1_g → A1_u and D′2_g → A′2_u) transitions can occur, has been carried out. It has been shown that the I₂(D → X, β → A and D′ → A′) luminescence is due to ArI₂(E ← B) transitions with subsequent predissociation. We have determined the spectroscopic parameters of the ArI₂(E,ν_E = 0–3) complexes. It has been shown that rate of vibrational predissociation is ∼10 times less than total rate of the ArI₂(E,ν_E = 0–3) → Ar + I₂(D, β, D′) electronic predissociation.