Description of the KLL Auger–Meitner decay spectra of argon following primary and satellite core-ionized states

The K-edge photoelectron and KLL Auger–Meitner decay spectra of Argon have been investigated computationally at the restricted active space perturbation theory to the second order level using biorthonormally transformed orbital sets. Binding energies were computed for the Ar 1s primary ionization, as well as for satellite states originated from shake-up and shake-off processes. Based on our calculations, the contributions of shake-up and shake-off states to the KLL Auger–Meitner spectra of Argon have been completely elucidated. Our results are compared with recent state-of-the-art experimental measurements on Argon.