Abstract
Strong field photoelectron holography has been proposed as a means for interrogating the spatial and temporal information of electrons and ions in a dynamic system. After ionization, part of the electron wave packet may directly go to the detector (the reference wave), while another part may be driven back and scatters off the ion(the signal wave). The interference hologram of the two waves may be used to extract target information embedded in the collision process. Unlike conventional optical holography, however, propagation of the electron wave packet is affected by the Coulomb potential as well as by the laser field. In addition, electrons are emitted over the whole laser pulse duration, thus multiple interferences may occur. In this work, we used a generalized quantum-trajectory Monte Carlo method to investigate the effect of Coulomb potential and the nonadiabatic subcycle ionization on the photoelectron hologram. We showed that photoelectron hologram can be well described only when the effect of nonadiabatic ionization is accounted for, and Coulomb potential can be neglected only in the tunnel ionization regime. Our results help paving the way for establishing photoelectron holography for probing spatial and dynamic properties of atoms and molecules.
Highlights
Strong field photoelectron holography has been proposed as a means for interrogating the spatial and temporal information of electrons and ions in a dynamic system
The results show that side lobes from quantum-trajectory Monte Carlo (QTMC) are less well developed than those obtained from time-dependent Schrödinger equation (TDSE) and generalized quantum-trajectory Monte Carlo (GQTMC)
For side lobes considered here, the reference wave is the direct electron emission while the signal wave is due to electrons that have been rescattered by the ion
Summary
Strong field photoelectron holography has been proposed as a means for interrogating the spatial and temporal information of electrons and ions in a dynamic system. Besides the familiar ATI peaks, new additional “peaks or fringes” have been observed in the two-dimensional electron momentum spectra These new features, usually are called by some new acronyms or by “structures”, appear to be quite general, as they are nearly independent of the target atoms or molecules, but they are dependent on the laser wavelength, intensity and sometimes on the pulse duration. In most cases the widely used strong field approximation (SFA) is incapable of interpreting these observations For such low-energy electrons, it is intuitively clear that a quantitative theory would require the incorporation of Coulomb potential from the ion core. Among them we will focus on the so-called “side lobes” observed in the photoelectron momentum distribution (PMD) Such side lobes were observed in the PMD of metastable xenon atoms ionized with intense 7000 nm free-electron lasers[12]. The QTMC method treats ionization under the quasistatic approximation and may agree with experiments in the deep tunneling regimes only, i.e., for γ 120
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