Attosecond two-photon double ionization of H2 molecule in full dimensionality

• Autores: Kilian Arteaga Gutiérrez
• Directores de la Tesis: Alicia Palacios Cañas (dir. tes.), Fernando Martín García (dir. tes.)
• Lectura: En la Universidad Autónoma de Madrid ( España ) en 2024
• Idioma: inglés
• Número de páginas: 146
• Títulos paralelos:
  • Doble ionización de H2 por absorción de dos fotones en la escala de attosegundos. Simulaciones incluyendo todas las dimensiones
• Enlaces
  • Tesis en acceso abierto en: Biblos-e Archivo
• Resumen

  • Attosecond spectroscopic techniques are nowadays able to experimentally unravel the role of nuclear motion and electron correlation in excitation and ionization processes in molecules on the ultrashort time scale. An accurate description of the interaction of intense short light pulses with molecular systems necessarily implies the solution of the time-dependent Schrödinger equation in a configuration space that comprises all break-up channels. The resolution of the time-dependent Schrödinger equation in full dimensionality for molecules represents a non trivial task. Even for the smallest molecule, H2. The main difficulty relies on the fact that, for solving the problem of molecular double ionization, it is mandatory to solve the four-body coulomb break-up to include all the possible paths and be able to extract the observables of the double ionization from the out-going wave packets. On this work, we have implemented a new computational tool allowing us to describe for the fist time, the multiphoton double ionization of H2 including nuclear motion. The method accounts for all possible channels resulting upon the interaction of attosecond pulses with the hydrogen molecule (all single and double ionization channels, dissociative excitation of highly excited states - autoionizing states, etc). Some of these problems have remained unsolved until now. The implemented software tools employ a description of the wave function written in a basis set of FE-DVR (finite elements combined with a discrete variable representation). Moreover, we have used an exterior complex scaling procedure to impose the appropriate many-body Coulomb boundary conditions in a defined volume. We present accurate angle and energy differential two-photon double ionization yields for the hydrogen molecule. First, we have found significant displacements, in energy and angle in the photoelectrons emission, with respect to the commonly used fixed nuclei approximation. The nuclear motion affects the correlated emission of electrons, and the signatures associated to a two-photon sequential versus non-sequential absorption of the two photons that lead to double ionization even using ultrashort driving pulses of less than 2 fs duration. One can expect that these effects will become even more pronounced for longer pulses and especially for one- and two-color pump-probe schemes