RESUMEN
In order to develop a high sensitive and low cost metal elements analysis method for aqueous sample, an ultrasonic nebulizer assisted spark induced breakdown spectroscopy (UN-SIBS) system is established, where an ultrasonic nebulizer is employed to transform the bulk liquid sample into aerosol composed by intensive droplets. And a high tension coil and a couple of electrodes are combined to induce the plasma. The spectra emitted are collected to analysis the metal elements in the aqueous samples. Based on the experimental system, the features of emission spectra are studied. The electron density and electron temperature are calculated to understand the physics characteristic of the plasma in UN-SIBS experiments. Samples of different concentration of lead are analyzed by UN-SIBS method to make clear of the relationship between concentration and the peak intensity of the heavy metal element Pb. Besides, the atomic line of lead at 261.37 nm detected by the sample with the concentration of 2.07 ppt could be easily distinguished which is better than the LOD reported in references. The aqueous samples with calcium, as a lower activity metal element, are also studied. At last, the possible mechanism is discussed according to the experimental results.
RESUMEN
In order to develop a method to analyze the metal elements in the thin film samples rapidly, directly and without sample preparation, a laboratory LIBS system was established recently for nanometer film analysis. This system could determine the position of sample plane, observe the profiles of sample after pulse-material interaction and detect the plasma morphologyand spectral emission at the same time. Samplesused were ZrO2 films about 40 nm thickness prepared on Si by a sol-gel process, and they were located on a manual X-Y-Z translational stage with theaccuracy of 0. 01 mm. Final results showed that the positional accuracy is about 20µLm with the help of two CW lasers, and the RSD of repeatability of single-shot spectra could be to 1. 6%. We investigated special morphology of plasma, variation tendency of signal intensity as a function of pulse energy, LTSD (laser focus to sample distance) and time, which provide cornerstone for optimizing experimental parameters under the conditions of room temperature and atmospheric pressure. We calculated plasma temperature by way of Boltzmann curve and electron density through the acquired data. We also appraised necessary LTE conditions for quantitativeanalysis.
RESUMEN
Because of the complex factors in bulk water, the effect of LIBS on the analysis of liquid sample is limited in liquid sample. Under this circumstances, a new method of LIBS assisted by ultrasonic nebulizing technology has been introduced. According to this method, the liquid sample is transformed into dense droplets by ultrasonic nebulizing technology, and these dense droplets are subjected to the analysis of LIBS later. Based on this thought, a detection experimental system was established, composing of ultrasonic system, 1 064 nm ND: YAG laser, and ICCD system. A series of experiments and analysis were carried out to detect the magnesium element dissolved in pure water using the detection experimental system mentioned above. The results showed that even with a very low laser pulse energy (30 mJ), the signals of LIBS still have a long lifetime and a high signal to background ratio. The limit of detection for magnesium element could reach as low as 0.242 ppm. At the same time, the electron density of plasma was calculated utilizing the Halpha line to give the evolution features of plasma induced by this new method.