Stepwise electron emission from autoionizing magnesium Stark states

We report on investigations of time dependent autoionization of doubly excited magnesium atoms in a strong electric field. A narrow band laser excites one electron towards a 3s16k Stark state and, subsequently, the second electron is excited with a short laser pulse. The autoionizing electron yield shows a stepwise decay which is detected by a streak camera with picosecond resolution. Quantum calculations are in good agreement with the experimental results.