No abstract

In this work, the KLL dielectronic recombination (DR) processes of highly charged He-like to O-like xenon ions are studied systematically by using a DR program, which is based on the multi-configuration Dirac—Fock (MCDF) method. The KLL DR resonant energies and the corresponding resonant strengths are calculated, emphasizing especially the effect of the Breit interaction on the DR strengths. The theoretical KLL DR spectra are obtained and compared with the latest experimental results obtained in the Shanghai Electron Beam Ion Trap.

In the process of nuclear waste disposal, the valuable uranium and plutonium are recycled and separated by dissolving the spent fuel in nitric acid. However, transuranic Np greatly influences the process of separation and recovery. Therefore, it is vital to study the structure and properties of nitrate, which is combined with neptunium ions and nitric acid. Furthermore, there are few researches about nitrate formed by tetravalent neptunium ions. So in this article, by using B3LYP hybrid method of density functional theory, the Gaussian 03 program is used to optimize the geometric construction of the coordination compounds Np(NO3)nq (n=1-6, q=-2-+3) formed by the tetravalent neptunium ions (Np4+) and nitrate ion (NO3-). Under the relativistic effective core potential model, the structure parameters and properties are reported. It is found that NO3- coordinates to Np4+ as a bidentate ligand, and the NpN and NpO bonds are the shortest in Np(NO3)22+, while the binding energy of the Np(NO3)4 is the largest. The infrared spectra of Np(NO3)4 are calculated in the gas and liquid phase. Comparing with the available experimental data, the reliability of the calculation results in this work is confirmed.

The electron-impact excitation (EIE) cross-sections of 5s2S1/2 → 5p2P3/2 of Cd+ have been calculated by using the relativistic distorted-wave (RDW) method which we have developed recently. In order to discuss the electronic correlation effects, four different models are used to describe the target wave functions, namely Model A, 8S, 5SD and 6SD. Model A is a single configuration model, it includes 5s1/2, 5p1/2 and 5p3/2 only. The 8S is a valence-valence correlation model, it considers the impacts of 6s, 7s, 8s and 6p, 7p, 8p orbitals on wave function of 5s1/2, 5p3/2, respectively. The 5SD is a core-valence correlation model, it includes all the virtual single and double excitations from the 4s, 4p, 4d, 5s and 5p shells into the unoccupied 4f, 5p, 5d, and 5f shells. The 6SD is also a core-valence correlation model, it includes all the virtual single and double excitations from the 4s, 4p, 4d, 5s and 5p shells into the unoccupied 4f, 5p, 5d, 5f, 6s, 6p and 6d shells. The oscillator strength calculated by Model A is 0.72, which is in disagreement with the experiment 0.55 measured by Xu et al., while the results of 6SD 0.57 is in agreement with these of the experiment very well. For the EIE cross-sections, the core-valence correlation is very important. The results of Model A and 8S are larger than the experimental results obtained by Gomonai et al., while the results of 5SD and 6SD is obviously smaller than the results of Model A. In low energy range (2P3/2 → 5s2S1/2 emission lines after excitation are very small, while the linear polarization of Model A, 5SD and 6SD are in consistent with each other and also in good agreement with other theories. But for high energies, the theoretical results have big difference from the experimental results obtained by Goto et al.