Weigold, Erich. Electron momentum spectroscopy / Erich Weigold and lan E. McCarthy. p. cm. --(Physics of atoms and molecules) Includes bibliographical references and index.

We present orientation-dependent stereo Wigner time delays of CO molecules, which reveal the electron localization at the ionization moment. Together with theoretical calculations this constitutes a spatially-and temporally-resolved reconstruction of the molecular photoelectric effect.

Nature 431, 437--440 (2004) In Figs 2 and 3 of this Letter, we calculated the angle between the molecular axis and the in-plane electron as Q e,mol 5 Q mol -Q e , where Q e and Q mol are the angles of the electron and the molecular axis with respect to the polarization vector e. This distribution was then rotated by the angle of the molecular axis to picture the electron emission in the polar plots. Here a sign error occurred: instead of calculating and plotting Q mol -Q e,mol 5 Q e , we presented Q mol 1 Q e,mol 5 2Q mol -Q e . Figure 1 illustrates the corrected results (compare with Figs 2, 3 in our Letter). The data now show an even stronger dependence of the angular distribution of the electrons on the molecular orientation, emphasizing the importance of the new internal reference axis. Thus, the angular distribution in Fig. 1a does not resemble a helium-like dipole pattern any more (as we stated originally), which would be aligned mainly along the polarization axis, but shows a preferred emission of electrons rectangular to the molecular axis.

Attosecond photoionization delays have mostly been interpreted within the single-particle approximation of multi-electron systems. The strong electron correlation between the photoionization channels associated with the 3p and 3s orbitals of argon presents an interesting arena where this single-particle approximation breaks down. Around photon energies of 42 eV, the 3s photoionization channel of argon experiences a "Cooper-like" minimum, which is exclusively the result of inter-electronic correlations with the 3p shell. Photoionization delays around this "Cooper-like" minimum have been predicted theoretically, but experimental verification has remained a challenge since the associated photoionization cross section is inherently very low. Here, we report the measurement of photoionization delays around the Cooper-like minimum that were acquired with the 100 kHz High-Repetition 1 laser system at the ELI-ALPS facility. We report relative photoionization delays reaching up to unprecedented values of 430±20 as, as a result of electron correlation. Our experimental results are in partial agreement with state-of-the-art theoretical results, but also demonstrate the need for additional theoretical developments.

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Abstract:The dynamics of helium double ionization by 2 keV electron impact has been investigated experimentally and theoretically at large momentum transfer of |q| = 2 a.u. Fully resolved fivefold differential cross sections (FDCS) are presented for symmetric and asymmetric energy sharing between the two ejected electrons at excess energies from 10 eV to 40 eV, and for the coplanar as well as the out-of-plane scattering geometries. Experimentally, a multielectron -recoil-ion coincidence technique has been applied and a large part of the final-state momentum-space has been mapped. The presently employed theoretical model treats the interaction between the two slow ejected electrons nonperturbatively using the convergent close coupling (CCC) method, whereas the projectile-target interaction is described in the first Born approximation. The experimental and theoretical FDCS agree well in shape. The cross section is dominated by two pairs of strong peaks. From this pattern it can be concluded that the two-step 1 mechanism which is due to interelectron interaction after a single ionizing collision is the dominant ionisation process for the present kinematics.2

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