Photoionization of atomic ions

Abstract

The development of both theoretical and experimental work on the photoionization of atomic ions over the last 20 years forms the subject of this review. The availability of spectroscopic measurements and, more recently, absolute cross sections provides a critical test of theoretical calculations, with implications for the modelling of stellar atmospheres, and for astrophysical and laboratory plasmas for which fundamental data of this kind are required.

Absolute cross sections for photoionization of Xeq +ions (1 ⩽ q ⩽ 5) at the 3d ionization threshold

“…The well-established photon-ion merged-beams technique [40][41][42][43][44][45][46] has been employed at the newly built Photon-Ion spectrometer at PETRA III (PIPE, figure 1) [47,48]. This experimental setup has been permanently installed as an end station at the "Variable Polarization XUV Beamline" (P04) of the synchrotron light source PETRA III at DESY in Hamburg, Germany.…”

“…Both beams overlapped well. For the evaluation of the overlap factor F L , the integrals are approximated by sums and the usual approximation [43,45] is made that the ion current density and the photon flux density factorize such that i ion (x, y) = i interpolating the three measured form factors F (z i ) with a second order polynomial (figure 5).…”

Absolute cross sections for L-shell photoionization of the ions N$\mathsf{^{2+}}$, N$\mathsf{^{3+}}$, O$\mathsf{^{3+}}$, O$\mathsf{^{4+}}$, F$\mathsf{^{3+}}$, F$\mathsf{^{4+}}$ and Ne$\mathsf{^{4+}}$

“…In consequence, the number of ions for which cross-section data are available is increasing rapidly, with experiments being performed in Denmark 4+ (ASTRID, Kjeldsen et al 1999b), France (SuperACO, Bizau et al 2000), Japan (Photon Factory, Koizumi et al 1995;SPring-8, Yamaoka et al 2002) and USA (ALS, Covington et al 2001). For a review of the previous works, see West (2001). In particular, the experiments performed on L-shell photoionization include the ions B + (Schippers et al 2003), C + (Kjeldsen et al 1999a(Kjeldsen et al , 2001), C 2+ (Müller et al 2002), N + (Kjeldsen et al 2002a), O + (Kjeldsen et al 2002a;Covington et al 2001;Aguilar et al 2003), O 2+ -O 4+ (Champeaux et al 2003), and Ne + (Covington et al 2002).…”

Photoionization of atomic and molecular positively charged ions

“…Only the advent of high photon flux available at synchrotron radiation facilities has allowed the experiments to develop. First, merged beam setups have been used, allowing the determination in absolute values of PI cross sections for ions with charge stage up to 9 [4,5]. One difficulty of this technique consists in an ionic target often composed of a mixture of ions in the ground and metastable states.…”