EXCITATION AND STABILITY OF ULTRAHIGH RYDBERG STATES IN STRAY ELECTRIC-FIELDS

We demonstrate the feasibility of exciting long-lived, circular Rydber g states by time dependent weak electric fields such as might be encou ntered in typical ZEKE-PES (zero-electron-kinetic-energy photoelectron spectroscopy) conditions. Through a geometric interpretation of the d ynamics, we identify the field configurations needed for either the st ability or the excitation of ultra-long-living Rydberg states and conc lude that nonuniform stray fields could be (partially) responsible for the observed, anomalously long lifetimes exhibited by ultrahigh Rydbe rg states, although under typical ZEKE-PES conditions other mechanisms like, for example, ion-Rydberg collisions constitute the main stabili zation agent.