We introduce the concept of photoionization time delay and present measurements in different atomic systems, with high spectral resolution. Both non-resonant and resonant photoionization dynamics will be considered.
We extend Fano’s propensity rule to two-photon above-threshold ionization and apply it to angle-resolved attosecond interferometry. This results in incomplete interference which lead to angle-dependent photoionization time delays and delay-dependent photoelectron angular distributions.
Using a circularly polarized Attosecond Pulse Train (APT) together with a weak replica of the circularly polarized fundamental Infra-Red (IR) we reconstruct the ionization phase of the (2s2p)$^1$P$^{\mathrm{o}}$ resonance in atomic Helium by analyzing the photelectron momentum distribution.
Tailored bicircular fields mimic linearly polarized light three times per period, while avoiding recollision and interferences. Combined with streaking, we extract momentum-dependent times of strong-field ionization even in the previously inaccessible range of rising field.
We experimentally resolve a time delay of electron wave packets arising from one-photon transitions in the continuum. This proves the influence of the outgoing wave packet spatial expansion on the photoionization delay.
Photoionization time delays between the 3s and 3p subshells of argon have been measured over a large energy range (34-70 eV) covering the Cooper minima in both subshells, providing stringent tests for interchannel correlation theories.
