Theoretical study of the photoionization of metastable neon

We have calculated the photoionization cross section for the $\left(1\mathrm{}{s}^{2}2s^{2}2p^{5}3s\right){}_{}{}^3{}_{}{}^{}P$ metastable state of neon using ab initio, many-electron wave functions in the $\mathrm{LS}$-coupling scheme. We have considered all the channels which arise from the $\left(1\mathrm{}{s}^{2}2s^{2}2p^5\right){}_{}{}^2{}_{}{}^{}P$ state of ${\mathrm{Ne}}^{+}$ and an ejected $p$ electron. The continuum was made discrete by approximating the final states as superpositions of square-integrable configurations. The Stieltjes moment-theory technique was used to construct the continuum oscillator strength distribution. Both the dipole-length and the dipole-velocity forms of the cross section were evaluated. We have examined systematically the effects of orbital relaxation, core polarization, and electron correlation and found them to be important within 5 eV of threshold. The peak value of the photoionization cross section for metastable Ne is 1.9 × ${10}^{-19\mathrm{}}$ ${\mathrm{cm}}^2$, which is much smaller than the corresponding value for the ground state. We have also calculated the line strengths for a few bound-bound transitions as well as the static polarizability of the ${}_{}{}^3{}_{}{}^{}P$ metastable state.