1s(2s2pP1)P2nl,1s(2s3sS3,1)S2np, and1s(2s3pP1)P2nsK-shell photoexcited Rydberg series of beryllium atoms

The inner-shell photoexcitation of the Rydberg series of Be atoms is explored from both experimental and theoretical points of view. We used synchrotron radiation to photoionize Be atoms and the time-of-flight method to record charge-separated photoion yield spectra. Many new autoionizing resonance peaks were observed in the ${\mathrm{Be}}^{2+}$ and ${\mathrm{Be}}^{+}$ spectra. They were categorized as Rydberg series members converging to the $1s(2s2p\phantom{\rule{0.2em}{0ex}}^{1}P^{o})^{2}P^{o}$, $1s(2s3s\phantom{\rule{0.2em}{0ex}}^{3}S)^{2}S$, and $1s(2s3s\phantom{\rule{0.2em}{0ex}}^{1}S)^{2}S$ series limits. Furthermore, numerical calculations using multiconfiguration Dirac-Fock (MCDF) method enabled us to assign unknown resonance peaks as the $1s(2s3p\phantom{\rule{0.3em}{0ex}}^{3}P^{o})^{2}P^{o}ns$ series members. The calculation of the ground state of Be atoms revealed that the admixture of the $1{s}^{2}2{p}^{2}$ into the ground state amounts to 8.67%.