# Attosecond transient absorption of a bound wave packet coupled to a smooth continuum

Title | Attosecond transient absorption of a bound wave packet coupled to a smooth continuum |

Publication Type | Journal Article |

Year of Publication | 2017 |

Authors | Dahlström, JMarcus, Pabst, S, Lindroth, E |

Journal | Journal of Optics |

Volume | 19 |

Pagination | 114004 |

Abstract | We investigate the possibility of using transient absorption of a coherent bound electron wave packet in hydrogen as an attosecond pulse characterization technique. In a recent work, we have shown that photoionization of such a coherent bound electron wave packet opens up for pulse characterization with unprecedented temporal accuracy—independent of the atomic structure—with maximal photoemission at all kinetic energies given a wave packet with zero relative phase (Pabst and Dahlström Phys. Rev. A 94 13411 (2016)). Here, we perform numerical propagation of the time-dependent Schrödinger equation and analytical calculations based on perturbation theory to show that the energy-resolved maximal absorption of photons from the attosecond pulse does not uniquely occur at a zero relative phase of the initial wave packet. Instead, maximal absorption occurs at different relative wave packet phases, distributed as a non-monotonous function with a smooth ##IMG## [http://ej.iop.org/images/2040-8986/19/11/114004/joptaa8a93ieqn1.gif] {$-π /2$} shift across the central photon energy (given a Fourier-limited Gaussian pulse). Similar results are also found in helium. Our finding is surprising, because it implies that the energy-resolved photoelectrons are not mapped one-to-one with the energy-resolved absorbed photons of the attosecond pulse. |

URL | http://stacks.iop.org/2040-8986/19/i=11/a=114004 |