Pressure-induced multiphoton ionization of krypton–argon mixtures at 248 nm

Pressure-induced three-photon ionization of Kr atoms at 248 nm has been examined in mixtures involving Ar and Ne. This density-dependent effect is attributed to the role of a two-photon near resonance, which, although forbidden by parity in the free atom, acquires an allowed character in the two-center molecular system. The response of Ar/Kr mixtures was greater than that observed in pure krypton. It was found that these effects reveal both the detailed structure of the near-resonant molecular states and the variation of the participating matrix elements with internuclear separation. It was also determined that the three-body recombination of Kr* to Kr*2 when assisted by Ar, is governed by a rate constant whose value is (3.0±0.7) ×10−32 cm6/sec.