Photoionization time delays

International audienceThe material presented in this chapter is based on important advances realized in " attophysics " which make feasible to follow the motion of electrons in atoms and molecules with attosecond-level time resolution. In this context, time-delays have been recently determined in the process of photoionization by extreme-ultraviolet (xuv) pulses and the question of the significance of these measured delays arises. As we shall outline here, numerical experiments show that they are intimately related to the structure of the ionized species' continuous spectrum. Another point addressed here is that, in experiments, the measurements have the common characteristic to be performed in the presence of an auxiliary infra-red (IR) field, used to " clock " the timing of the process. This implies to adapt the theory treatment to handle such " two-color " photoionization processes. We review a systematic analysis of these features that are characteristic of this class of electronic transitions, when viewed in the time domain

Génération et caractérisation d'impulsions attosecondes

Résumé françaisRésumé anglaisORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Théorie de l'ionisation des atomes en champ laser intense (étude des structures observées aux hautes énergies)

PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Théorie de l'ionisation de l'atome d'hydrogène dans les champs électromagnétiques intenses (lasers et collisions)

PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

IONISATION MULTIPHOTONIQUE XUV-IR (ETUDES ET APPLICATIONS A LA MESURE D'IMPULSIONS XUV FEMTO ET ATTO SECONDES)

PARIS-BIUSJ-Physique recherche (751052113) / SudocCentre Technique Livre Ens. Sup. (774682301) / SudocSudocFranceF

Etude et applications des propriétés de cohérence du supercontinuum et des harmoniques d'ordre élevé

PARIS-BIUSJ-Thèses (751052125) / SudocSudocFranceItalyFRI

Laser-assisted (e, 2 e) collisions in helium

The influence of a strong laser field on the dynamics of fast (e, 2 e) collisions in helium is analyzed in the asymmetric, coplanar geometry. The interaction of the laser field with the incident, scattered and ejected electrons is treated in a non-perturbative way, while the remaining interactions are treated by using first order perturbation theory. Detailed calculations are performed for an incident electron energy Eki=600 eV, an ejected electron energy EkB=5 eV and a scattering angle θA=4°. The influence of the laser parameters (photon energy, intensity and direction of polarization) on the angular distribution of the ejected electron is analyzed. We find that in general the triple differential cross sections are strongly dependent on the dressing of the projectile and the target by the laser field. © 1992 Springer-Verlag.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Comment on "Photoionization of helium atoms irradiated with intense vacuum ultraviolet free-electron laser light. Part II. Theoretical modeling of multiphoton and single-photon processes"

We question the conclusions reached by De Castro [Phys. Rev. A 72, 023410 (2005)] regarding the theoretical analysis of experimental results by Laarman [Phys. Rev. A 72, 023409 (2005)] on photoionization of He in the presence of a strong free-electron laser radiation pulse