Ab initio - calculated streaked and angle-resolved direct and shake-up photoemission spectra for helium

Understanding the correlated ionization dynamics in atoms has remained a challenging

task. By implementing an adaptive FE-DVR method to efficiently solve the two-electron

time-dependent Schrödinger equation, we calculated ab initio attosecond time-resolved spectra for

streaked XUV photoemission from helium. For the n=2 shake-up channel, we find photoemission time-delays relative to direct photoemission in agreement with the experimental and calculated results of

M. Ossiander et al [Nature Phys 13, 280 (2017)] and provide relative photoemission delays for the n=3 shake up channel. Within a multipole expansion and by comparing our ab initio results for angle-resolved spectra with a simplified single-active-electron calculation, we examine the contributions of the lowest multipole orders of the residual He+(n=2,3) charge distributions on the photoemission delay.