Electronic spectroscopy of the Ẽ← transition of NO–Kr and shielding/penetration effects in Rydberg states of NO–Rg complexes

Abstract

We report the results of a (2 + 1) resonance-enhanced multiphoton ionization (REMPI) study of the Ẽ²Σ⁺(4sσ) Rydberg state of NO–Kr. We present an assignment of the two-photon spectrum based on a simulation, and discuss it in the context of previously-reported spectra of NO–Ne and NO–Ar. In addition, we report on spectra in the region of the v_NO = 1 level of the Ẽ, and ′ 4s and 3d Rydberg states of NO–Rg (Rg = Ne–Kr). Since the NO vibrational frequency is affected by electron donation from the rare-gas (Rg) atom to the NO⁺ core, as well as by the penetration of the Rydberg electron, the fundamental NO-stretch frequency reflects the interactions in the complex. The results indicate that the 4s Rydberg state has a strong interaction between the NO⁺ core and the Kr atom, as was the case for NO–Ar and NO–Ne. For the 3d Rydberg states, although penetration is not as significant as for the 4s Rydberg states, it does play an important role, with subtle angular effects being notable.