Ionization of the σ*2s orbital of NO and configuration interaction effects on the spin-split states arising from inner orbital ionization in paramagnetic molecules

Abstract

Two Rydberg series of bands of NO which converge to a common limit at 175200+or-50 cm^-1 (21.721+or-0.006 eV) have been found in absorption in the range 680-560 AA. The limit agrees with an ionization peak occurring at this energy in its photoelectron spectrum. The ionization is interpreted as leading to the formation of the ( sigma *2s)^-1, ³ Pi state of No⁺. No comparable band systems which could be assigned as Rydberg bands approaching the corresponding singlet state. This phenomenon is attributed to configuration interaction affecting preferentially the low multiplicity component of spin-split stages. It appears to be a common feature of the inner valence orbitals of many paramagnetic molecules and their ions. The diffuseness and Fano type profiles of many of the bands of NO show that the life-times of the states are very short due to predissociation and autoionization.