Analytical model for attosecond time delays and Fano's propensity rules in the continuum

BOLL, D.I.R.; MARTINI, L.; FOJÓN, O.A.

Physical Review A

American Physical Society

Lugar: New York; Año: 2022 vol. 106

2469-9926

Extracting single photoionization time delays associated with atomic (or molecular) species from attosecond timescale two-photon experiments usually relies on the theoretical description of continuum-continuum transitions. The available models for those processes predict a universal phase contribution, independent of the angular quantum numbers of final states. However, a recent experimental-theoretical study [Fuchs, Optica 7, 154 (2020)2334-253610.1364/OPTICA.378639] determined a sizable time-delay dependence on the angular momentum of near-threshold photoelectrons. In this paper, we present an analytical model for the two-photon two-color transition matrix amplitudes that reproduces the phase dependence on the angular quantum number of final states. Finally, we show that our analytical model can also describe the generalized Fano´s propensity rules [Busto, Phys. Rev. Lett. 123, 133201 (2019)0031-900710.1103/PhysRevLett.123.133201] for laser-assisted photoionization.