Libs; Soil analysis; Practical powder sample holder; Quantitative powder analysis;ATOMIC EMISSION-SPECTROMETRY; SPECTROCHEMICAL ANALYSIS; PLASMA; LIBS; ABLATION; MATRIX; METALS; PB

A practical alternative of sample preparation technique is proposed for direct powder analysis using laser-induced breakdown spectroscopy (LIBS) instead of the commonly adopted treatment of pelletizing the powder. The resulted pellet is known to suffer from reduced sensitivity of emission. Besides, it may also give rise to interfering effect from the binder emission. We introduce in this report a more practical technique of using a subtarget supported micro mesh (SSMM) powder sample holder. The LIBS spectrum of standard soil powder measured with 13 mJ 1064 nm Nd:YAG laser in 0.65 kPa ambient air is shown to exhibit the sharp emission lines of all the major elements in the sample. A comparison with the emission spectra measured from the pelletized powder, the spectrum obtained using the SSMM sample holder shows distinctly superior spectral quality marked by the absence of matrix effect found in pelletized powder samples, and the much stronger intensity due to the more effective shock wave plasma induced thermal excitation process produced by the hard subtarget in the sample holder. Repeating the measurement on a number of the standard soil samples of various Pb contents is shown to yield a linear calibration line with practically zero intercept and a detection limit of less than 10 ppm. We have thus demonstrated the viability of the proposed powder sample holder for the development of practical and quantitative powder analysis in the field. (C) 2017 Elsevier B.V. All rights reserved.

The aim of this research is to figure out an activated zeolite ability to immobilize Pb element in liquid sample. The zeolite was made into powder with size of about 400 mu m and was activated by NaOH with different concentrations of 0.5, 1, 1.5 and 2 M. Prior to being analyzed by commercial Laser-InducedBreakdown Spectroscopy (LIBS) technique, 0.05 gram activated zeolite of each concentration were soaked into 10 ml solution containing 100 ppm of Pb and then heated and stirred until become dry powder. The powder was then made into a pellet. After being analyzed by LIBS, activation by 1.0 M NaOH was the optimum condition for zeolite to immobilize Pb in solution. The minimum concentration of Pb in liquid sample which could be immobilized by this method was about 5.86 ppm.

HELIUM GAS PLASMA; QUANTITATIVE-ANALYSIS; DEUTERIUM

A study of hydrogen and oxygen and its reaction with host elements in a sandstone has been done by laser-induced breakdown spectroscopy (LIBS). The sandstone was irradiated by Nd-YAG laser (1064 nm, 7 ns) with varied energy of 60 mJ till 140 mJ in surrounding air gas pressure of 1 atm and produced plasma. The emission intensities of hydrogen H I 656.2 nm and oxygen O I 777.2 nm in the plasma were captured by HR 2500(+) spectrometer and displayed in intensity as a function of wavelength. The data show that the emission intensities of hydrogen and oxygen increase with increasing laser energy at a gradient of 5.4 and 11.8 respectively every increasing laser energy of 20 mJ. To characterize the reaction process between hydrogen and oxygen with the host elements of the sandstone, a 0.2 ml demineralized water was dropped on the sandstone surface and was analyzed as a function of delay time reaction and temperature. The data show that the oxidation reaction between host elements and oxygen occurred after 25 minutes that the oxygen emission intensity increases and the hydrogen emission intensity decreases. Another data also show that the increasing temperature of sandstone until 80 degrees C increased intermolecular bond between oxygen and host element and dehydrogenation took place after reaching this temperature

DUAL-PULSE LIBS; INDUCED PLASMA; ABLATION EFFICIENCY; SENSITIVE ANALYSIS; HELIUM PLASMA; FEMTOSECOND; ENHANCEMENT; NANOSECOND; MICROANALYSIS; DEUTERIUM

A time-resolved spectroscopic study is performed by using 125-500 micro-Joule (mu J) ps laser focused directly without the aid of microscope on a Cu plate sample in a variety of low-pressure ambient gases including air, helium and argon. It is shown that the ultrashort mu J laser-induced low-pressure plasma in Ar ambient gas exhibits the typical characteristics of shock wave plasma responsible for the thermal excitation and sharp emission of the analyte atoms. It is found that the highest signal to background (S/B) ratio of about 100 is achieved in 1.3 kPa argon ambient gas and detected with optical multichannel analyzer (OMA) gate delay of 1 ns and gate width of 50 mu s. The emission spectra obtained from pure Zn sample show the effective suppression of the ionic emission with ablation energy around and below 500 mu J. The experimental setup is successfully applied to Cr analysis with low detection limit in steel. In particular, its application to C analysis in steel is demonstrated to resolve the long standing problem of overlapping contributions from the neutral and ionic Fe emission. It is further found that an element of high excitation energy such as fluorine (F) can be clearly detected from a non metal teflon sample. Further, its application to alluminum sample containing various concentrations of Mg, Ca, Fe, and Si impurity elements clearly displays the existence of linear calibration lines promising for quantitative analyses in certain dynamical ranges. Finally, in view of the tiny crater sizes of less than 10 mu m diameter created by the very low ps laserenergy, this technique is promising for micrometer resolution mapping of elemental distribution on the sample surface and its depth profiling. (C) 2017 The Japan Society of Applied Physics

INDUCED BREAKDOWN SPECTROSCOPY; QUANTITATIVE-ANALYSIS; PULSE; HELIUM; LIBS; CONFIGURATION; MICROANALYSIS; ENHANCEMENT; DEUTERIUM; NM

An experimental study is performed on the time-dependent intensity variations of Zn emission focusing on the triplet (Zn I 481.0 nm) and singlet (Zn I 636.2 nm) emission lines induced under three experimental conditions. A single nanosecond (ns) Nd:YAG laser in standard laser-induced breakdown spectroscopy(LIBS) setup is employed for the investigation of direct shock wave-induced emission characteristics with N-2 ambient gas at 0.4 kPa and the different effects of He ambient gas at 2 kPa. An additional two-laser system consisting of ns and picosecond (ps) lasers in an orthogonal setup is used to study the exclusive role of a He-assisted excitation (HAE) process for the generation of those two Zn emission lines. The results of this study consistently exhibit the dominant triplet emission over the singlet emission marked by initial maximum intensity ratios of 8 and 12 obtained from the experiments using a single-laser setup in N-2 and He ambient gases, respectively, indicating the significant contribution of the HAE mechanism to the enhanced and longer lasting Zn emission in He gas. The experiment using the special two-laser setup further demonstrates the exclusive role of the HAE process in the Zn emission featuring an even markedly higher triplet/singlet intensity ratio of 22. Thus, the results of this study suggest the possibly more general nature of dominant triplet emission phenomena previously found in laser-induced He and Ca emission spectra. (C) 2017 The Japan Society of Applied Physics

DOUBLE-PULSE; QUANTITATIVE-ANALYSIS; INDUCED PLASMA; DEUTERIUM; ABLATION; CHAMBER; GAS

An experimental study is conducted in search of the much needed experimental method for practical and minimally destructive analysis of hydrogen (H) and deuterium (D) in a nuclear power plant. For this purpose, a picosecond (ps) Nd:YAG laser is employed and operated with 300-500 mu J output energies in a variety of ambient gases at various gas pressures. The sample chamber used is specially designed small quartz tube with an open end that can be tightly fitted to the sample surface. It is found that ambient Ar gas at reduced pressure of around 0.13 kPa gives the best spectral quality featuring fully resolved H and D emission lines with clearly detectable intensities and practically free from surface water interference. The D emission intensities measured from zircaloy plates containing various concentrations of D impurity are shown to yield a linear calibration line with extrapolated zero intercept, offering its potential application to quantitative analysis. The estimated detection limit of less than 10 ppm is well below the sensitivity limit of around 600 ppm required for the regular inspection of zircaloy tubes in a heavy water nuclear power plant. The use of the exceedingly low laser energy is shown to offer an additional advantage of minimum destructive effect marked by the resulted tiny craters of about 5 mu m diameter with 25 mu m depth. These results promise the potential development of the desired alternative analytical tool for regular in situ and real time inspection of the zircaloy tubes in a heavy water power plant.