Photoionization study of Kr⁺and Xe⁺ions with the combined use of a merged-beam set-up and an ion trap

Abstract

To cite this version:J M Bizau, C Blancard, M Coreno, D Cubaynes, C Dehon, et al.. Photoionization study of Kr+ and Xe+ ions with the combined use of a merged-beam set-up and an ion trap. Journal of Physics B: Atomic, Molecular and Optical Physics, IOP Publishing, 2011, 44 (5) Introduction:Atomic physics provides unique tools for plasma diagnostics. In particular, based on photoionization studies on ionic species one can deduce essential spectroscopic data for the determination of important plasma parameters such as abundance and temperature. In addition, dipole selection rules allow further simplification of the data by reducing the number of allowed transitions. To be useful, quantities like the energies and oscillator strengths of discrete lines or direct photoionization cross sections must be measured in absolute value with high accuracy for a large number of ionic species and over a wide range of photon energy. Photoionization is also one of the main processes contributing to plasma opacity and radiation transfer inside plasmas.

Atomic data for neutron-capture elements

“…We substantially improved our calculated Kr + PI cross section through comparison with the experimental data of Bizau et al (2011). In Fig.…”

“…) at the Advanced Light Source synchrotron radiation facility, for the purpose of constraining our calculations. PI investigations were previously carried out for Kr 3+ to Kr 5+ (Lu et al 2006a,b;Lu 2006), and more recently for Kr + (Bizau et al 2011). We compare our computed PI cross sections to these measurements to benchmark and gauge the accuracy of our direct PI cross sections.…”

“…The measurements were conducted at a variety of synchrotron radiation facilities, and in the case of ionized species utilized the merged beams method. Kr 3+ through Kr 5+ PI cross sections were measured at the Advanced Light Source synchrotron radiation facility at the Lawrence Berkeley National Laboratory in California (Lu et al 2006a,b;Lu 2006), while that of Kr + was recently measured at the ASTRID storage ring at the University of Aarhus in Denmark (Bizau et al 2011). These measurements were complicated by the population of metastable states in the primary ion beams, and hence the measured cross sections are a linear combination of those from the ground and metastable states.…”

“…These measurements were complicated by the population of metastable states in the primary ion beams, and hence the measured cross sections are a linear combination of those from the ground and metastable states. However, Bizau et al (2011) used an ion trap to significantly limit contributions from the 2 P 1/2 metastable state, and measured the Kr + ground state PI cross section over a limited energy range. In the case of neutral Kr, we compare our results to the PI cross sections recommended by Richter et al (2003), which were determined from measurements of the PI and electron-impact ionization cross section ratio and normalized to the double ion chamber PI measurements of Samson & Yin (1989) and Samson et al (1991).…”

Photoionization of atomic and molecular positively charged ions

“…The sharp lines correspond to photoexcitations of a 5p electron to empty nd or ns orbitals, leaving a Xe + ion in 5p 4 nd,ns highly excited levels which will decay via autoionization to the ground state of Xe 2+ ion [6,17]. The vertical bars above the spectrum indicate the position of the Xe + 5p -1 ionization thresholds [18]. A strong signal is visible at lower photon energy than the first ionization threshold at 20.98 eV, clearly demonstrating the contribution of Xe + ions in metastable states to our spectrum.…”