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A selection from Stockholm University publication database

• Study of the possibilities with combinations of circularly and linearly polarized light for attosecond delay investigations

  2020. Johanna Sörngård, J. M. Dahlström, Eva Lindroth. Journal of Physics B 53 (13)

  Article

  We present calculations on the atomic delay in photoionzation obtained with different combinations of linearly and circularly polarized light, and show how a tensor operator approach can be used to readily obtain results for any combination from a single calculation of the radial integrals. We find that for certain choices of polarization and detection geometry a single time-delay measurement is enough to extract the atomic delay since the relative phase in a RABBIT type measurement will be imprinted on the photo electron anisotropy. We show further that the full angular dependence can be qualitatively understood from a plane wave analysis. The results are illustrated by many-body calculations of two-photon above threshold ionization on argon.

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• Angular anisotropy parameters for photoionization delays

  2021. Soumyajit Saha (et al.). Physical Review A: covering atomic, molecular, and optical physics and quantum information 104 (3)

  Article

  Anisotropy parameters describing the angular dependence of the photoionization delay are defined. The formalism is applied to results obtained with the relativistic random phase approximation with exchange for photoionization delay from the outermost s-orbitals in selected rare-gas atoms. Any angular dependence in the Wigner delay is induced here by relativistic effects, while the measurable atomic delay exhibits such a dependence also in the nonrelativistic limit. The contributions to the anisotropy from the different sources are disentangled and discussed. For the heavier rare gases, it is shown that measurements of the delay for electrons ejected in specific angles, relative to, e.g., those ejected along the laser polarization, are directly related here to the Wigner delay. For a considerable range of angles, the contributions from the second photon largely get canceled when the results in different angles are compared, and this angle-relative atomic delay is then close to the corresponding Wigner delay.

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