Retrieval of the amplitude and phase of the dipole matrix element by attosecond electron-wave-packet interferometry

摘要

We extend the ideas of wave-packet interferometry [Remetter et al., Nat. Phys. 2, 323 (2006)] to implementnthe algorithm of spectral phase interferometry for direct electric-field reconstruction (SPIDER) for characterizingnthe amplitude and phase of electron wave packets. Single-photon ionization by an attosecond pulse launchesnan electron wave packet in the continuum. Ionization by a train of two attosecond pulses in the presence of anmoderate infrared pulse creates an interferogram in the final photoelectron momentum distribution. From theninterferogram, the complex electron wave function can be reconstructed. If the pulses are well characterized, thenamplitude and phase of the bound-free dipole matrix element can be reconstructed over a wide energy range. Thisnis demonstrated by application of the retrieval method to momentum distributions obtained by numerical solutionnof the time-dependent Schr‥odinger equation. The case of Coulombic potentials requires appropriate treatment ofnthe laser-Coulomb coupled dynamics.