Determination of sub—ppm levels of boron in ground water samples by laser induced breakdown spectroscopy

Laser induced breakdown spectroscopy (LIBS) was applied to the determination of sub-ppm levels of boron in ground water samples using spectroscopically pure graphite planchets as solid support. The data obtained by LIBS agreed well with those from ICP-AES. No spectral interference due to the possibly interfering elements Fe, Cr, Al and Mo was observed. The detection limit was 0.01 µg.g^?1 for boron using the B(I) 249.773 nm emission line. The method is considered to be promising for the rapid determination of boron, with an acceptable degree of accuracy and without the need for elaborate sample treatment, preconcentration and purification steps.     

Instrumentation of kinetic spectroscopy-20: Cherenkov emission in a ‘foil’ of optical fibers to measure the excitation in pulse radiolysis

Cherenkov emission in a “foil” of optical fibers is utilized for measuring the excitation in pulse radiolysis experiments, i.e., the charge of the pulses of high-energy electrons which penetrate the foil perpendicularly. Because of the inherent response of Cherenkov emission, this method can be applied for the detection of electron pulses with durations as short as a few picosecond or longer. High sensitivity and high time resolution as well as excellent precision are provided by this method.     

Instrumentation of kinetic spectroscopy—7. A precision integrator for measuring the excitation in laser flash photolysis and pulse radiolysis experiments

An electronic circuit is described which integrates current against time with high resolution and precision. By connecting a suitable detector (a photodiode in laser flash photolysis experiments, or, either a secondary emission chamber or a current pick-up in pulse radiolysis experiments) to this circuit, the excitation can be measured. This integrator is suitable for the measurement of excitation over a wide range and is especially useful for monitoring extremely low values. The resulting is about 3E-12 As, which corresponds to initial radical concentrations of less than 1 nM in pulse radiolysis experiments.     

Geochemistry study of soil affected catastrophically by tsunami disaster triggered by 2004 Indian Ocean earthquake using a fourth harmonics (λ = 266 nm) Nd:YAG laser induced breakdown spectroscopy

In this work, laser induced breakdown spectroscopy (LIBS) analysis of the soil samples collected from Aceh, a place in Indonesia worst affected by 2004 Indian Ocean tsunami, was conducted. In the LIBS experimental system, a high energy pulsed laser beam was focused on the tsunami affected soil samples and the atomic emission lines, originating from the laser induced plasma were recorded using locally developed laser induced breakdown spectrometer. Our results show that the concentrations of many elements especially terrestrial markers, namely titanium, iron, and carbonate marker such as magnesium, are higher in the tsunami-affected samples than that in the unaffected samples collected from the same neighborhood. The quantification of Ti, Fe and Mg were carried out using Ti II 334.94, Fe I 438.35, and Mg I 277.98 nm atomic transition lines respectively by drawing the calibration curve by preparing the samples of known concentrations in unaffected soil matrix. In order to ensure accurate quantification, the local thermal equilibrium of the laser-induced plasma was verified using Mc Writher criterion, for which the plasma temperature was estimated using linearized Boltzmann plot for six iron atomic transition lines and the electron number density in the plasma was estimated using Stark broadened Fe I 540.4 nm atomic lines. The estimated temperature and electron number density of the laser induced plasma are 9642 K and 3.5 × 10¹⁶ cm^?3 respectively. The concentrations of Ti, Fe and Mg in tsunami unaffected soil are 0.09, 3.2 and 0.02 w/w% and in tsunami affected soil are 0.14, 7.9 and 0.048 w/w% respectively. These values are in good agreement with XRF data. The elemental ratios extracted from LIBS signal intensity revealed that LIBS emission intensity ratios of several elements, such as Si/Ti, Al/Ti and Sr/Ba are potential candidates as the distinctive geochemical signature for identification the soil impacted and unimpacted by the 2004 Indian Ocean giant tsunami. The advantage of using LIBS for the elemental analysis is that the sample can be analyzed in its pristine form without any need cumbersome sample preparation method, which has the risk of bringing in external additives through chemicals used for the sample preparation. Other advantages of LIBS technique are that the analysis can be in situ and can be carried out remotely.     

The impact of indium metal as a minor bimetal on the anodic dissolution and passivation performance of zinc for alkaline batteries. Part II: galvanostatic,impedance spectroscopy,and charge–discharge evaluations

Journal of Solid State Electrochemistry - The anodic dissolution and passivation processes of zinc and zinc-indium alloys were investigated in an alkaline solution of 6 M KOH using...     

Simultaneous determination of germanium,arsenic, tin and antimony with total-reflection X-ray fluorescence spectrometry using the hydride generation technique for matrix separation—first steps in the development of a new application

This paper introduces a new perspective for total-reflection X-ray fluorescence analysis (TXRF), that is the simultaneous determination of Ge, As, Sn and Sb in seawater. As is well known from atomic absorption spectroscopy (AAS) and inductively coupled plasma techniques (ICP) compounds of these elements can be reduced by sodium borohydride to their hydrides and thus separated from the matrix. In this work the hydride generation is used for matrix separation in TXRF measurements. For this purpose the following procedures are considered: (1) Preconcentration of hydrides by absorption in solvents, and evaporation of some μl of this solution on the sample carrier. (2) Decomposition of hydrides in a heated thin silica tube, or at rough and/or catalytically active surfaces, e.g. in adequately prepared columns, eluting of the species by acid and evaporation of some μl of this solution on the sample carrier. (3) Decomposition of hydrides directly on the surface of a heated silica sample carrier as a thin amorphous film. (4) Combustion of hydrides in the hydrogen flame and deposition of an elemental film on the sample carrier. Basically, all four ways have been tested and the results are promising. © 1997 Elsevier Science B.V.