IONIZATION OF VERY-HIGH-N RYDBERG ATOMS BY HALF-CYCLE PULSES IN THE SHORT-PULSE REGIME

The ionization of potassium Rydberg atoms with n similar to 388 and n similar to 520 by pulsed electric fields whose durations, which range from similar to 2 to similar to 110 ns, span the transition from the s hort-pulse to the long-pulse regime is investigated experimentally and the data compared with the results of classical trajectory Monte Carl o calculations. We observe excellent agreement between theory and expe riment providing a benchmark test for the validity of the classical li mit of ionization. Very-high-n atoms provide an excellent tool with wh ich to probe the response of atoms to pulsed electric fields in the sh ort-pulse regime.