Autoionizing Rydberg states in Na2

Abstract

Extended autoionization structure has been observed in sequential two‐photon ionization of Na₂ via different vibronic levels of the intermediate B ¹Σ_u state. Partial snalysis of this structure has now been achieved. A dominant Rydberg series (quantum defect δ = 0.4) and a second, weaker series (δ = 0.57) are assigned. Convergence to many different vibronic levels of the ion core is observed, allowing a preliminary determination of ω _e and ω_exPde for the Na₂^{+ 2}Σ⁺_g ground state. A difference of +49 cm⁻¹ between the spectroscopically extrapolated ionization potential and the previously observered ionization threshold is noted and discussed.