Photoionization of Xe and Xe@ C60 from the 4d shell in RABBITT fields

We consider photoemission from the 4d shell of the free Xe and encapsulated Xe@C60 atoms by ionizing XUV and probing IR fields typical for a RABBITT (reconstruction of attosecond beating by interference of two-photon transitions) measurement. Our theoretical model is based on the numerical solution of the time-dependent Schrödinger equation in the single-active-electron approximation. The fullerene C60 cage is represented by a finite-width well potential. We test our model against an analogous set of nonrelativistic [Phys. Rev. A 89, 053424 (2014)PLRAAN1050-294710.1103/PhysRevA.89.053424] and relativistic [Phys. Rev. A 96, 053407 (2017)2469-992610.1103/PhysRevA.96.053407] calculations for the 4d shell of Xe and Xe@C60 driven by a continuous XUV field. Based on this verification, we make predictions for the total ionization probability, angular anisotropy β parameter, and the angular-dependent atomic time delay τa from the threshold to several hundred eV of excess energy.