DP-LIBS; Double-ionized Al spectral lines; Electron impact excitation coefficient; De-excitation rate coefficients for Al ions;ABLATION; SINGLE; ATOMS; FIELD

We built a collinear dual-pulse laser-induced breakdown spectroscopy (DP-LIBS) system to study the aluminum (Al) plasma emission by installing a pair of Nd: YAG lasers operating at 266 and 1064 nm. The spectral intensities of selected aluminum doubly-ionized lines were employed to evaluate the optical emission spectra. The influences of the energy ratio of two pulsed lasers on the LIBS intensity for different Al doubly-ionized spectral lines were investigated. The de-excitation rate parameters of the excited ion and the electron impact excitation were computed using the analytical formulas proposed by Smeets and Vriens. The transition probabilities and energy states were computed using Hibbert's configuration interaction, computer package (CIV3). By solving the coupled rate equations including 1s(2)2s(2)2p(6)ns (S-2), 1s(2)2s(2)2p(6)np (P-2), 1s(2)2s(2)2p(6)nd (D-2) (n = 3-5) and 1s(2)2s(2)2p(6)nf (F-2) (n = 4, 5) states, the level population densities were computed. We also proposed a theoretical population model in order to investigate the effectiveness of the various processes that might affect the population of the upper levels in Al plasma by using the rate coefficients. In addition, the population densities for the 19 upper levels were also computed. Good compatibility between the experimental and the theoretical model data had been observed. Our results might be significant as reference data for the optimization of the DP-LIBS spectrometry and diagnostics of laser produced plasmas.

Plasma; Laser; EPR; DP-LIBS; Mn-analysis; PVA polymer;INDUCED PLASMA SPECTROSCOPY; INDUCED BREAKDOWN SPECTROSCOPY; SINGLE; EPR; IDENTIFICATION; ULTRAVIOLET; CRYSTALS; LIBS

Series of manganese-co-precipitated poly (vinyl alcohol) (PVA) polymer were quantitatively and qualitatively analyzed using laser ablation system (LAS) based on double-pulse laser induced breakdown spectroscopy (DP-LIBS) and electron paramagnetic resonance (EPR) spectroscopy. The collinear nanosecond laser beams of 266 and 1064 nm were optimized to focus on the surface of the PVA polymer target. Both laser beams were employed to estimate the natural properties of the excited Mn-PVA plasma, such as electron number density (Ne), electron temperature (T-e), and Mn concentration. Individual transition lines of manganese (Mn), carbon (C), lithium (Li), hydrogen (H) and oxygen (0) atoms are identified based on the NIST spectral database. The results show better responses with DP-LIBS than the single-pulse laser induced breakdown spectroscopy (SP-LIBS). On the other hand, the EPR investigation shows characteristic broad peak of Mn-nano-particles (Mn-NPs) in the range of quantum dots of superparamagnetic materials. The line width (peak-to-peak, triangle H-pp) and g-value of the observed Mn-EPR peak are similar to 20 mT and 2.0046, respectively. The intensities of Mn-emission line at a wavelength 403.07 nm and the Mn-EPR absorption peak were used to accurate quantify the Mn-content in the polymer matrix. The results produce linear trends within the studied concentration range with regression coefficient (R-2) value of similar to 0.99, and limit of detection (LOD) of 0.026 mol.% and 0.016 mol.%, respectively. The LOD values are at a fold change of about -0.2 of the studied lowest mol.%. The proposed protocols of trace element detection are of significant advantage and can be applied to the other metal analysis. (C) 2017 Elsevier Ltd. All rights reserved.

tungsten ion beam; double-pulse lasers ablation system; laser ablation system; optical Instrumentation;INDUCED BREAKDOWN SPECTROSCOPY; APPLIED ELECTRIC-FIELD; INDUCED PLASMA; SURFACE; SPECTROMETRY; DYNAMICS; WAVELENGTHS; NANOSECOND; PARAMETERS; RADIATION

New tungsten ion source is produced by using single and double-pulse laser ablation system. Combined collinear Nd:YAG laser beams (266+1064 nm) are optimized to focus on the sample in air. Optimization of the experimental parameters is achieved to enhance the signal-to-noise ratio of the emission spectra. The velocity distribution of the emitted plasma cloud is carefully measured. The influences of the potential difference between the bias electrodes, laserwavelength and intensity on the current signal are also studied. The results show that the increase in the tungsten ion velocity under the double-pulse lasers causes the output current signal to increase by about three folds. The electron density and temperature are calculated by using the Stark-broadened line profile of tungsten line and Boltzmann plot method of the upper energy levels, respectively. The signal intensity dependence of the tungsten ion angular distribution is also analyzed. The results indicate that the double-pulse laser ablation configuration is more potent technique for producing more metal ion source deposition, thin film formation, and activated plasma-facing component material.