Chair: François Légaré, INRS-EMT, Varennes, Canada

  • Pascal Salières
  • Sonia Erattupuzha
  • Catherine Lefebvre
  • Daniel Hickstein
  • Kevin Henrichs

#29, 13:30 – 14:00 Phase spectroscopy of resonant photo-ionization: Accessing attosecond delays and wavepacket dynamics, PASCAL SALIÈRES, The generation of attosecond pulses and the development of electron wavepacket interferometry have made it possible to measure the spectral phase of transition dipole moments, not accessible otherwise. Here, we show how these techniques can be used to access the dipole phase across resonances in the ionization continuum of atoms and molecules. We can then reconstruct the electron wavepacket as it is born in the continuum; its temporal profile exhibits fast oscillations due to interferences between resonant and non-resonant channels. These measurements also provide quantitative access to the attosecond delays in the resonant two-photon transitions.

#30, 14:00 – 14:15 Attosecond Spatial Control of Electron Wavepacket Emission Dynamics and Electron-Electron Correlation in Double Ionization, L. ZHANG, X. XIE, S. ROITHER, S. ERATTUPUZHA, D. KARTASHOV, M. SCHÖFFLER, D. SHAFIR, P. B. CORKUM, A. BALTUŠKA, A.STAUDTE AND M. KITZLER, Using orthogonally polarized two-color (OTC) laser fields on neon and coincidence momentum imaging we gain access to the Coulomb influence in single ionization on sub-cycle times, and demonstrate control over the two electron-emission dynamics in double ionization. We show that tuning the relative phase of the OTC fields allows dictating whether the two electrons are predominantly emitted in a correlated or anti-correlated manner.

#31, 14:15 – 14:30 Photoelectron momentum distribution from orthogonal two-color laser-induced ionization, C. LEFEBVRE, F. FILLION-GOURDEAU, K. OTANI, J.-C. KIEFFER, AND S. MACLEAN, We present a theoretical analysis of a pump-probe technique to study the dynamics of the photoelectron after tunnel ionization. We use a linearly polarized femtosecond infrared (IR) pulse to ionize a hydrogen atom and an orthogonal attosecond extreme-ultraviolet (XUV) pulse to induce a lateral shift in the photoelectron momentum distribution. The multidimensional interference pattern strongly depends on the pump-probe delay, on the duration and intensity of the pulses. This imaging technique gives information on the dynamical properties of the photoelectron, in particular its time of emission and its momentum content.

#32, 14:30 – 14:45 Strong-field physics in two-color circularly polarized fields, DANIEL D. HICKSTEIN, CHRISTOPHER A. MANCUSO, FRANKLIN DOLLAR, JENNIFER L. ELLIS, PATRIK GRYCHTOL, RONNY KNUT, OFER KFIR, XIAOMIN TONG, DMITRIY ZUSIN, MAITHREYI GOPALAKRISHNAN, CHRISTIAN GENTRY, EMRAH TURGUT, MING-CHANG CHEN, AVNER FLEISCHER, OREN COHEN, HENRY C. KAPTEYN, MARGARET M. MURNANE, Recent studies have revealed that high harmonic generation (HHG) can produce circularly polarized attosecond pulse trains when driven with twocolor counter-rotating circularly polarized laser field. Here we present the results of the first study of strong-field  ionization (the complementary process to HHG) of atoms in two-color circularly polarized fields, uncovering the mechanism for HHG under these conditions. We demonstrate the presence of prominent structures in the photoelectron angular distributions that correspond to field driven electron-ion rescattering, opening the door to uncovering molecular structure information. In addition, we explore the practicality of various methods for HHG using counter-rotating fields.

#33, 14:45 – 15:00 Electron Energy Discretization in Strong Field Double Ionization, K. HENRICHS, M. WAITZ, F. TRINTER, H.-K. KIM, A. MENSSEN, H. GASSERT, H. SANN, T. JAHNKE, J. WU, M. PITZER, M. RICHTER, M. S. SCHÖFFLER, M. KUNITSKI, AND R. DÖRNER, We study the double ionization of Argon and Helium at a wavelength of 394 nm. We found discretization in the sum energy of those ionized electrons for Argon. Additionally the individual energies of both electrons also show ATI-like structures. Therefore we propose that a doubly excited intermediate state has to be present. For Helium only weak discretization was visible at low intensities at 394 nm. Nevertheless, our highly differential data and high resolution allows for the study of the impact of parity and angular momentum transferred by the field.