Photoionization of MetastableO+Ions: Experiment and Theory

Abstract

High-resolution absolute experimental measurements and two independent theoretical calculations were performed for photoionization of O 1 ions from the 2 P o and 2 D o metastable levels and from the 4 S o ground state in the photon energy range 30-35.5 eV. This is believed to be the first comparison of experiment and theory to be reported for photoionization from metastable states of ions. While there is correspondence between the predicted and measured positions and relative strengths of the resonances, the cross-section magnitudes and fine structure are sensitive to the choice of basis states.

Photoionization cross sections of O II, O III, O IV, and O V: BenchmarkingR-matrix theory and experiments

“…The figure has seven panels: the lowest three panels, Figs. 1(a)-1(c [5] and by Kjeldsen et al [7], respectively. tinct resonance series seen in the low-energy region of Fig.…”

“…The convolved cross sections with experimental monochromatic bandwidth for 5 S o state are shown in Fig. 3(e).…”

“…[5][6][7][8]. Resonances can be identified using quantum defect analysis E r = E t − z 2 / 2 , where E r is the resonance energy, E t is the next core threshold energy in rydbergs, z = Z − n c is the ion charge of the target where n c is the number of core electrons, and = n − is the effective quantum number with being the quantum defect.…”

“…Each of these three sophisticated experimental setups has different advantages in measurements, and the results often complement each other. Cross sections for O II have been measured at ALS for nearthreshold features in PI of metastable states [5], and later extended to a wider photon energy range [6], and at the University of Aarhüs [7]. Detailed photoionization cross sections have recently been measured for the ground and low excited states of multiply charged oxygen ions for the first time for O III, O IV, and O V, at the synchrotron radiation source at University of Paris-Sud [8].…”

“…On the experimental side, accurate photoionization cross sections are being measured at several places, such as the merged ion-photon beam facility at the University of Aarhüs (e.g., for C II [3]), the Electron Cyclotron Resonant Ion Source (ECR) at the University of Paris-Sud (e.g., for Xe V-Xe VIII [4]), and the Advanced Light Source (ALS) at Berkeley (e.g., for O II [5]). Each of these three sophisticated experimental setups has different advantages in measurements, and the results often complement each other.…”