CORE SCATTERING OF STARK WAVE-PACKETS

We investigate the wave-packet dynamics of electrons bound in the nons eparable potential of cesium in a static electric field using time;dom ain Ramsey interferometry. Specially shaped wave packets with low radi al dispersion enable us to view the interaction between the wave packe t and the atomic core. Experiments in cesium, together with quantum de fect calculations of cesium and hydrogen, demonstrate changes in the m otion and shape of these wave packets due to core scattering.