Decay dynamics of high Rydberg states in atoms and molecules

Decay dynamics of high Rydberg states above the first ionization limit have been studied. The decay rate to the ionization continuum, due to spin orbit coupling for atoms (Ar), or coupling to the dense manifold of available rovibronic states in polyatomic molecules, was measured. This decay is non-exponential and can be influenced by external fields. The stabilization of very high (ZEKE) states is demonstrated and possible mechanisms accounting for these very long lived stated are discussed.