Excitation and Stability of Ultrahigh Rydberg States in Stray Electric Fields

We demonstrate the feasibility of exciting long-lived, circular Rydberg states by time dependent weak electric fields such as might be encountered in typical ZEKE-PES (zero-electron-kinetic-energy photoelectron spectroscopy) conditions. Through a geometric interpretation of the dynamics, we identify the field configurations needed for either the stability or the excitation of ultra-long-living Rydberg states and conclude that nonuniform stray fields could be (partially) responsible for the observed, anomalously long lifetimes exhibited by ultrahigh Rydberg states, although under typical ZEKE-PES conditions other mechanisms like, for example, ion-Rydberg collisions constitute the main stabilization agent.