Attosecond photoionization dynamics in the vicinity of the Cooper minima in argon
Using a spectrally resolved electron interferometry technique, we measure photoionization time delays between the 3s and 3p subshells of argon over a large 34-eV energy range covering the Cooper minima in both subshells. The observed strong variations of the 3s-3p delay difference, including a sign change, are well reproduced by theoretical calculations using the two-photon two-color random-phase