J.G. Zeibel and R.R. Jones
Abstract:Picosecond ``half-cycle'' pulses (HCPs) have been used to produce novel electronic wavepackets by recombining photoelectrons with their parent ions. The time-dependent momentum distributions of the bound wavepackets are probed using a second HCP and the Impulsive Momentum Retrieval (IMR) method. For a given delay between the initial photoionization event and the HCP recombination, classical trajectory simulations predict pronounced periodic wavepacket motion for a restricted range of recombining HCP amplitudes. This motion is characterized by the repeated formation and collapse of a highly localized spike in the 3-dimensional electron probability density at a large distance from the nucleus. Our experiments confirm that oscillatory wavepacket motion occurs only for certain recombination ``kick'' strengths. Moreover, the measured time-dependent momentum distributions are consistent with the predicted formation of a highly localized electron packet. We demonstrate a new variation of IMR in which amplitude modulation of the HCP probe field is employed to suppress noise and allow for a more direct recovery of electron momentum from experimental ionization data.
Status: Published Phys. Rev. A 68 023410(2003).