[en] Laser-induced breakdown spectroscopy (LIBS) has been applied to the analysis of heavy metals in liquid sample. A new approach was presented to improve the detection limit and minimize the sample matrix effects, in which dried wood pellets absorbed the given amounts of Cr standard solutions and then were baked because they have stronger and rapid absorption properties for liquid samples as well as simple elemental compositions. In this work, we have taken a typical heavy metal Cr element as an example, and investigated the spectral feasibility of Cr solutions and dried wood pellets before and after absorbing Cr solutions at the same experimental conditions, respectively. The results were demonstrated to successfully produce a superior analytical response for heavy metal elements by using wood pellet as sample matrix according to obtained LOD of 0.07 ppm for Cr element in solutions. (author)

[en] Using Nd: YAG laser (with a wavelength of 1064 nm and a pulse width of 10 ns) to ablate Cu target to get plasma spectra with different intensities of laser energy, authors observe the different changes of CuI and CuII spectra as follows: the intensities of the atomic and ions lines of Cu plasma spectra have different changes with the increase of laser energy. The intensities of all lines get to maximum when laser energy is 330 mJ/pulse, then there is a small flat between 330 and 370 mJ/pulse of laser energy, and subsequently, the intensities of all lines gradually decrease with further increase of laser energy. Meanwhile, under the model of local thermodynamic equilibrium (LTE), authors measure the electronic temperatures of Cu plasma at different intensities of laser energy according to the relative intensities of five lines. The results show that the temperature ascends monotonously from 1.02 x 10⁴ K to 1.46 x 10⁴ K with the increase of laser energy, then it decreases along the further increment of laser energy

[en] The plasma is produced by ablating Al target with Q-switch Nd:YAG Laser (wavelength 1.06 μm, pulse width 10 ns). Al emission spectrum are observed in the low air pressure and the direct electricity field. The influence of the spectral line intensity in various laser power density and direct electricity field is studied. The electron temperature of plasma in various laser power density and FWHM of the spectral line in direct electricity field are measured. The results show that the spectral line intensity of Al atom is increased prominently in direct electricity field. The FWHM of spectral line of Al atom in various additional voltage of direct electricity field is linear. (authors)

[en] Accurate data for dielectronic recombination of tungsten ions are essential in modeling of tungsten impurity transport and radiative power loss in International Thermonuclear Experimental Reactor (ITER). Theoretical calculations have been made for dielectronic recombination (DR) rate coefficients of Br-like tungsten ions using a flexible relativistic atomic code (FAC) from 1 eV to 50 keV. Level-by-level calculations are carried out for evaluating the contributions to DR through all the relevant Kr-like tungsten ions autoionizing inner-shell excited configuration complexes: (3s"23p"63d"1"0)"-"14s"24p"5nln'l' (n = 4 - 5, n' = 4 - 100, l' = 0 - 8), (4s"24p"5)"-"1nln'l' (n = 4 - 6, n' = 4 - 100, l' = 0 - 12). Comparison of the rate coefficients for 3s, 3p, 3d, 4s and 4p subshell excitations shows that the 4p subshell excitation dominates over the whole temperature region, 4s subshell excitation at low temperature and 3d, 3p subshell excitations at high temperature can not be neglected. In order to facilitate simple applications, the total DR rate coefficient, Δn = 0, 1 and 2 core excitations DR rate coefficients are fitted to a empirical formula. (author)

[en] A time resolved laser induced breakdown spectroscopy technique (LIBS) was used for the investigation of emission signal enhancement on double-pulse LIBS. Two Q-switched Nd:YAG lasers at 1064 nm wavelength have been employed to generate laser-induced plasma on aluminium-based alloys. The plasma emission signals were recorded by spectrometer with ICCD detector. Spectral response calibration was performed by using deuterium and tungsten halogen lamps. Time evolution of the plasma temperature and electron density was investigated in SP and DP experiments. Based on the investigation of plasma parameters, the enhancements of emission line intensities were investigated, and the mechanisms of it were discussed. (author)

[en] Using Nd:YAG laser (with a wavelength of 1064 nm and a pulse width of 10 ns) ablate copper target in air to observe the emission spectra of plasma. The space-resolved spectra are measured in the wavelength of 440 nm to 540 nm at the different laser energy. Under the model of local thermodynamic equilibrium, the electronic temperature of Cu plasma is deduced to be in the 10⁴ scale by the relative line intensities. Finally, space characteristics of electron temperature are obtained near the target, the strength and FWHW (the full width half maximum) of N(II) 500.52 nm spectral line are analysed. (authors)

[en] The photoabsorption spectra of gold and iodine ions have been recorded using the Dual Laser-produced Plasma (DLP) technique in the 65 to 125 eV region, and the EUV emission spectra of tin ions have also been observed. With the aid of multiconfiguration Hartree-Fock calculations, the measured spectra have been identified. The dominant features in the gold spectra are 4f - 5d, 6d and 5p - 5d transitions arrays, while the iodine spectra arise from 4d - nf excitation, which evolves from 4d - εf shape resonance. The EUV spectra of tin plasma have also been simulated by combining the calculations of atomic data using the cowan code and a steady-state collisional radiative (CR) model. (author)

[en] Based on the Multi-configuration Dirac-Fock method, theoretical calculations have been performed for the dielectronic recombination (DR) rate coefficients of Sn⁵⁺ - Sn¹³⁺ ions. It is found that the total DR rate coefficient has its maximum value between 10 eV and 100 eV and is greater than either the radiative recombination (RR) or three-body recombination rate coefficients (the number of free electrons per unit is 10²¹cm³) for Sn⁷⁺ - Sn¹³⁺ ions at T_e >10 eV. Therefore, DR can strongly influence the ionization balance of laser produced multi-charged tin ions. (author)

[en] Detailed theoretical calculations are performed for the 4f and 5p inner-shell excitations of W-W³⁺ ions using the multiconfiguration Hartree-Fock method in order to better understand the origin of the XUV photoabsorption spectra of W atoms from the dual laser-produced plasma experiment (Costello et al. J. Phys. B 24 (1991) 5063 and the spectra of photon-induced single ionization of W^q+ ions (q = 1, 2, 3) (Meuller et al. Phys. Scr. T1441 (2011) 014052) from photon-ions merged beam experiments, respectively. Two broad and strong resonances in the experimental spectra have also been theoretically identified mainly from 5p-5d resonance. The 4f-5d, 6d and 5p-6d transitions also make a small contribution to each spectrum, which are superimposed on the 5p-5d transition arrays. Based on the assumption of a normalized Boltzmann distribution among the excited states, we succeed in reproducing spectra which are in good agreement with experiments. (authors)

[en] Photoabsorption spectra of iodine and gold plasmas were recorded using the dual laser produced plasma technique. In the case of iodine, the spectra were dominated by 4d excitation and contributions from stages up to four times ionized were observed. For gold, the spectra obtained could be assigned to 5p and 4f excitation in Au⁺ to Au⁴⁺. The main spectral features were identified by comparison with atomic structure calculations.