Evidence of orbital mixing for KrXe and ArXe excited states in the vacuum ultraviolet

Abstract

The dissociation limits for two KrXe Rydberg states near 80000 cm⁻¹ have been reassigned using single-photon vacuum ultraviolet (VUV) laser resonance enhanced multiphoton ionization (REMPI)/time-of-flight (TOF) mass spectrometry. These new assignments follow from spectral intensity changes that occur when the excited states are populated by single-photon excitation instead of a two-photon transition. The observations can be rationalized on the basis of strong 6p–5d orbital mixing on the Xe center induced by ground state Kr in the excited state of the dimer. ArXe transitions in this region have also been found by (1 + 1′) REMPI. There is also strong intensity evidence here for strong p–d mixing. Isotopic transition wavenumbers for the newly observed ArXe bands are provided, but molecular constants have not been derived due to severe interstate perturbations. Where possible the relationship between these results and our current understanding of the rare gas kinetics leading to gain in the infrared Xe laser is discussed.