THE ROLE OF THE QUANTUM-DEFECT AND OF HIGH-ORDER DISPERSION IN RYDBERG WAVE-PACKETS

Experimental and theoretical recurrence spectra of Rydberg electron wa ve packets are presented. Fractional revivals up to the seventh order are observed. In addition we observe a new interference effect: a fore runner wave packet in the first full revival, due to second-order disp ersion. Also it is shown that the quantum defect of rubidium shifts th e peaks in the interference pattern by the quantum defect module one t imes the classical orbiting period, while it leaves the envelope of th e recurrence spectrum unaffected. All these quantum mechanical effects are explained by a Taylor expansion of the phase factors of the stati onary states of which the wave packet is composed.