Abstract
We present a numerical study of the ultrafast ionization dynamics of exposed to attosecond extreme ultraviolet (xuv) pulses that goes beyond the Born-Openheimer approximation. The four-dimensional, time-dependent Schrödinger equation was solved using a generalization of the finite-element discrete-variable-representation/real-space–product technique used in our previous calculations to include the dynamical motion of the nuclei. This has enabled us to expose the target to any polarized light at arbitrary angles with respect to the molecular axis. Calculations have been performed at different angles and photon energies ( up to 630 eV) to investigate the energy and orientation dependence of the photoionization probability. A strong orientation dependence of the photoionization probability of was found at a photon energy of . At this energy, we found that the ionization probability is three times larger in the perpendicular polarization than in the parallel case. These observations are explained by the different geometric “cross sections” seen by the photoejected electron as it leaves the molecule. This ionization anisotropy vanishes at the higher-photon energy of . When these higher-energy xuv pulses are polarized perpendicular to the internuclear axis, a “double-slit-like” interference pattern is observed. However, we find that the diffraction angle only approaches the classical formula , where is the diffraction order, is the released electron wavelength, and is the internuclear distance, when becomes less than 65% of . These results illustrate the possibility of employing attosecond pulses to perform photoelectron microscopy of molecules.
6 More- Received 13 May 2009
DOI:https://doi.org/10.1103/PhysRevA.80.023426
©2009 American Physical Society
Viewpoint
Illuminating molecules from within
Published 31 August 2009
Calculations show that with new short pulse x-ray light sources, it should be possible to use photoelectron emission to make movies of changes in molecular structure.
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