Electron angular distributions in near-threshold atomic ionization

• Published in: Journal of physics. B, Atomic, molecular, and optical physics Atomic, molecular, and optical physics, 2010-05, Vol.43 (9), p.095601-095601
• Main Authors: Marchenko, T, Muller, H G, Schafer, K J, Vrakking, M J J
• Format: Article
• Language: English
• Subjects: Angular distribution; Atomic and molecular physics; Atomic properties and interactions with photons; Exact sciences and technology; Femtosecond; Fundamental areas of phenomenology (including applications); Ionization; Kinetic energy; Lasers; Mathematical models; Multiphoton ionization and excitation to highly excited states (e.g., rydberg states); Optics; Photoelectrons; Photon interactions with atoms; Physics; Quantum optics; Schroedinger equation; Strong-field excitation of optical transitions in quantum systems; multi-photon processes; dynamic stark shift
• ISSN: 0953-4075; 1361-6455
• DOI: 10.1088/0953-4075/43/9/095601

We present angle- and energy-resolved measurements of photoelectrons produced in strong-field ionization of Xe using a tunable femtosecond laser. An occurrence of highly oscillatory patterns in the angular distribution at low photoelectron kinetic energy is observed that correlates with channel closing/opening over a wide range of laser parameters. The correlation is investigated both experimentally and by means of systematic analysis of numerical solutions of the time-dependent Schrodinger equation. Our experimental and numerical results are in quantitative agreement with the semi-classical model introduced by Arbo et al (2008 Phys. Rev. A 78 013406), which relates the oscillatory patterns to interference between photoelectrons produced during different cycles of the laser pulse in the course of non-resonant ionization of the atom. We observe that an increase of the laser intensity eventually leads to qualitative invariance of the pattern, defining a limit on the applicability of the semi-classical model.