Kr (n=5-10,s,d,g) electronic wave packets: Electron time-of-flight resolution and the ac-Stark shift during wave-packet preparation

A two-color (3+1[prime]) pump-probe scheme is used to create Rydberg wave packets in krypton atoms. The ac-Stark shift, caused by the high intensity pump pulse, allows access to states with principal quantum numbers n=5–10 over a broad energy range. States shifted by as much as 3000 cm–1 during the pump pulse are coherently excited, resulting in wave-packet superpositions of field free states. By resolving the kinetic energy of the photoelectrons produced in the ionization probe step, numerous quantum beats are resolved and assigned. In addition, the energies of four previously unmeasured g states are determined.