Analytical possibilities of elemental analysis of water solutions based on the emission spectrum of a laser spark on the surface

Abstract

The possibilities of spectrochemical methods of analysis of substances using lasers for atomization were investigated in detail in [1-4]. In particular, the formation and development, in both time and space, of a laser spark on the surface of metals and solid dielectrics were studied in detail [5, 6]. The investigations showed that the emission line spectrum of the laser plasma arises after the continuous background emission pulse, which lasts for several hundreds of nanoseconds [7]. The efficiency of excitation of the atoms and ions formed and the temporal characteristics of their emission depend on the power of the laser pulse [8, 9]. In addition, the ratio of the line and continuous emission intensities depend significantly on the spatial arrangement of the emitting zone in the plasma flame. All these investigations have shown that the contrast of the emission spectrum can be significantly increased [i0, ii] by optimizing the plasma flame formation process (by changing the density of the medium into which the material vaporized by the laser radiation expands, using two irradiation pulses, and optimizing the spatial and time intervals for the measurements), and in the process the relative detection limit can reach a value of the order of 10-5% [6, 7], while the sensitivity of the direct laser spectral analysis, which is of the order of 0.01% [4], is too low.