RYDBERG TRANSITIONS INDUCED BY OPTICAL CORE DRESSING

We study theoretically the behavior of two atomic Rydberg series, coup led by a light field that strongly drives the optical transition betwe en the core states to which these series converge. It is shown that th is strong-held version of isolated-core excitation leads to a Strong m odification of the photoionization spectrum and to transitions between adjacent Rydberg states when the Rabi frequency associated with the c ore transition becomes larger than the Rydberg spacing. The intensitie s and pulse durations (approximate to 2 GW/cm(2) and 1 ps, respectivel y, for n approximate to 20 Rydberg states) needed for the observation of these effects are within reach of present-day lasers.