Molecule effect in inner shell sequential double ionization

We present a theoretical framework for the angular distribution of the two emitted photoelectrons in sequential inner shell two-photon double ionization (TPDI) of uniformly distributed molecules. As an example, we numerically calculated the sequential double ionization of the 4d shells of the iodine atom in CH3I with a length and velocity gauge and obtained the corresponding angular anisotropy parameters. For comparison, we also compute the anisotropy parameters for atomic xenon. The anisotropy parameter for the second ionization of CH3I is strongly influenced by the molecular structure, providing a sensitive probe for photoionization dynamics in polyatomic systems. This study provides a computational code for simulating sequential TPDI processes, enabling one to computationally study the molecular effects in the angular distribution for sequential inner-shell double ionization.