Electric Field Ionization of High Rydberg States of Ar with Sequences of Identical Pulses

Novel field-ionization behavior of very high Rydberg states of Ar ( n0ex0ex=0ex0ex50--250) is observed using sequential pulsed electric fields. Fast autoionization acts as a filter against adiabatic field ionization near the ²P1/2 threshold, whereas both diabatic and adiabatic field ionization occur near the ²P3/2 threshold. Sequences of up to 9 equivalent pulses yield recurrent field ionization signals near the ²P3/2 threshold, provided that the field returns close to zero between pulses, demonstrating a statistical redistribution of the Rydberg population amongst all states of a given Stark manifold near zero field.