Theoretical study on structures and bond properties of NpO2(m+) ions and NpO2(H2O)n(m+) (m = 1-2, n = 1-6) complexes in the gas phase and aqueous solution.

The equilibrium structures, vibrational frequencies, and bond characteristics of NpO2(m+) ions and NpO2(H2O)n(m+) (m = 1-2, n = 1-6) complexes have been studied by carrying out ab initio calculations in the gas phase and aqueous solution. The geometries have been obtained at the B3LYP level with the use of the polarized continuum model (PCM). The computed structural parameters that are in reasonably good agreement with the available data show that the solvation effect leads to a red shift of the IR spectra and the weakness of interaction strengths in neptunyl ions. By comparing the structural properties and the density of states (DOS) of these aqua complexes in the gas phase and aqueous solution, it is found that the solvation effect can be simulated approximately with the calculations of these aqua complexes in the gas phase. In addition, the DOS of these aqua complexes together with the binding energies between the neptunyl ion and water molecule reveal that the penta-aqua complex is preferred for neptunyl ions in aqueous solution.

[Spectroscopic study of laser induced breakdown plasma spectroscopy in air and semi-empirical simulation].

A laser induced breakdown spectroscopy experiment was carried out using Nd:YAG laser in air, and time-resolved spectra were measured. Based on local thermodynamic equilibrium assumption, a method used to simulate LIBS spectra is proposed. A LIBS spectrum of air in the wavelength range of 700~900 nm was simulated using this method. A good agreement between experiment and simulation was obtained, and moreover, the relative concentrations of the N, O and Ar in air were obtained.