of the C$^{3+}$ and F$^{6+}$ ions with Hylleraas-type calculations [@YTD], see Table V. Note that the Hy-CI energy values of the $P$-states are very accurate, showing that the Hy-CI wave function is very advantageous for the calculation of states with non-zero angular momentum. With this method the accuracy of higher excited states of the lowest symmetries (like it is the case of $8P$, $8D$ which are not listed in Table IV) is lower than the accuracy of low-lying excited states of higher symmetry, i.e. $8F$, $8G$, …, $8K$. The reason is the state $8K$ is the first solution of the eigenvalue equation for a wave function of K-symmetry, while i.e. $8P$ is the seventh solution of its corresponding Schrödinger equation. In this respect, one can observe innacuracies in the obtained energy of the weakly bound Rydberg states.

With the data of Table IV we have drawn the spectral diagrams of these ions, see Figs. 3 and 4. We have scaled these diagrams taking for every one the ground state energy level as lowest point and the limit of inonization as highest point, and calculating the position of the states with respect to this interval. Therefore we can compare the relative 