Primitive calculations, based on simple physical concepts, have been found to explain the unusual excited state potential energy curves deduced from RgXe (Rg = Kr, Ar, Ne), two-photon spectra. The irregularities in the potentials and their dependence on the effective principle quantum number, n*, are attributed to repulsive exchange interactions between electrons in closed shell orbitals of the ground state Rg atom and the Xe* Rydberg electron. The internuclear distance dependence of these exchange interactions reflect the nodal structure of the radial probability distribution of the Rydberg orbital.