Redistribution of Rydberg states by intense picosecond pulses

Abstract
Starting with Ba atoms in one Rydberg state we have observed the population of adjacent Rydberg states when the atom is exposed to an intense 1.5-ps laser pulse. The initial Rydberg state population is redistributed by a Raman-like two-photon process, rather than simply being photoionized. This population trapping, which is associated with stabilization against ionization, is described in terms of Rydberg antiwave packets.