Doubly excited electron-ion angular momentum transfer in parity-unfavored multiphoton ionization

Abstract

We observe the parity-unfavored photoelectron emission in multiphoton single ionization of krypton atoms in an intense ultraviolet laser field. With systematic experiments of successively varying the light ellipticity and intensity, we identify that this parity-unfavored emission is associated with the first excited ionic state via a resonant pathway. We reveal an abnormal Coulomb asymmetry of the parity-unfavored photoelectron emission in elliptically polarized fields when the ellipticity is less than 0.3. The simulation using the time-dependent Schr\odinger equation based on single-active-electron approximation fails to reproduce the experiment. We attribute the experimental observations to the angular momentum correlation between the resonantly excited electron and the spin-orbit excited ion. Our results demonstrate that the well-known picture of the angular momentum transfer in multiphoton ionization is broken and instead that the electron shares the spin angular momenta of photons with the ion as an effect of electron correlations.