An experimental and theoretical study of the 3p_3/2 level of atomic cesium: Beyond the one‐electron picture

A 3p_3/2 binding energy of 1005.0±0.3 eV has been measured in atomic cesium by x‐ray photoelectron spectroscopy using Al Kα radiation. The same binding energy has been calculated as the difference between the total energies of the 3p_3/2 hole state and the ground state using the Dirac–Fock program of Desclaux, minus the difference between the correlation energies of the two states. The correlation energy for the final 3p_3/2 hole state has been found to be 2.17 eV greater than the correlation energy for the ground state using configuration interaction with the form of the correlated wave function dictated by first order perturbation theory. The resulting theoretical binding energy of 1005.70 eV is in good agreement with experiment.