Note on the3p54s3dConfiguration in Neutral Potassium (K i)

Intermediate coupling matrices for $p^5\mathrm{sd}$ were diagonalized with energy parameters based on restricted Hartree-Fock wave functions for K i $3p^{5}4s3d$. The resulting energies and Russell-Saunders percentage compositions for the levels are given. The baricenter of the configuration was taken as 170 644 ${\mathrm{cm}}^{-1\mathrm{}}$, equal to the average energy relative to $3p^{6}4s$ as calculated by the Hartree-Fock method. Three autoionization lines previously observed in the vacuum ultraviolet absorption spectrum of K i are classified as transitions to levels of $3p^{5}4s3d$. An approximate correction of -2025 ${\mathrm{cm}}^{-1\mathrm{}}$ to the above baricenter is thus obtained, and predicted positions for the other transitions to $3p^{5}4s3d$ are given. The doublet $3p^{6}4s{}_{}{}^2{}_{}{}^{}S_{\frac{1}{2}}^{}{}_{}{}^{}\to 3p^{5}3d\left({}_{}{}^1{}_{}{}^{}P°\right)$ $4s{}_{}{}^2{}_{}{}^{}P_{\frac{1}{2},1\mathrm{}\frac{1}{2}}^{°}{}_{}{}^{}$ (calculated position ∼ 480 Å) is predicted to absorb most of the oscillator strength of the array. The calculated percentage compositions of the levels confirm a conclusion of Sprott and Novick that the ${}_{}{}^4{}_{}{}^{}D_{3\frac{1}{2}}^{}{}_{}{}^{}$ level observed by them does not belong to $3p^{5}4s3d$. Calculated positions for $3p^{5}4s3d$ and $3p^{5}4s4p$ are consistent, within the approximations, with their conclusion that $3p^{5}4s3d{}_{}{}^4{}_{}{}^{}F_{4\frac{1}{2}}^{°}{}_{}{}^{}$ and $3p^{5}4s4p{}_{}{}^4{}_{}{}^{}D_{3\frac{1}{2}}^{}{}_{}{}^{}$ are not separated by more than ∼ 0.15 eV.