Autoionizing decay of H<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow/><mml:mn>2</mml:mn></mml:msub></mml:math>doubly excited states by using xuv-pump–infrared-probe schemes with trains of attosecond pulses

Abstract

We present a theoretical study of H${}_{2}$ ionization by a pump-probe scheme consisting on an attosecond pulse train (APT) and a near-infrared (IR) pulse. We focus on the autoionization dynamics of the first series of resonant states of the molecule, the Q${}_{1}$ doubly excited states. The APT central frequency is tuned to populate the ${}^{1}{\ensuremath{\Sigma}}_{u}^{+}$ resonant states. The trace of autoionization is clearly visible in the two-dimensional (2D) proton-electron coincidence spectra and in the proton kinetic energy spectra. The dynamics of the autoionization process is clearly visible in the movie obtained by plotting the 2D spectrum as a function of the time delay between the APT and IR pulses. An analysis of the final symmetries ${\ensuremath{\Sigma}}_{g}$ and ${\ensuremath{\Sigma}}_{u}$ allows us to track the origin of the different structures.