ИСТИНА

The Curve of growth (COG) methodology was firstly applied to laser-induced plasma (LIP) approximately 20 years ago [1,2]. The idea implies registration of emission signal of the self-absorbed line for the set of the samples with a different mass concentration of the investigated element c(El). Then, the fitting of the experimental curve (the line intensity IL vs. c(El)) by theoretical equation using the specific model of LIP is performed. If the plasma temperature T, electron density ne, and optical path length l, and transition probability A and Stark broadening parameter wS/ne of the line are known, we can deduce the coefficient of proportionality between cel and its species number density n(El) in the LIP from the fitting. In the present study, we suggest an alternative approach for the obtaining of the COG. Namely, we produce LIP by focusing the laser beam by a cylindrical lens into the line and observe the plasma in the end on configuration (fig. 1). By varying and controlling the LIP length with the help of the diaphragm we can obtain the emission signal with the different degree of absorption and construct the COG in the coordinates l–IL. Thus, we use only one and the same sample in our measurements. Knowing the T, ne, A and wS/ne, we can fit experimental COG by two parameters (the coefficient of experimental setup and nel) equation for the IL. We have obtained the COGs for Li and Cu on the example of the Mg alloy. We have found n(Li)=1.9e16 and n(Cu)=4.3e13 cm^−3. The experimental ratio n(Li):n(Cu) was in agreement with the atomic ratio in the solid sample: 440±110 vs. 364. References [1] I.B. Gornushkin, J.M. Anzano, L.A. King, B.W. Smith, N. Omenetto, J.D. Winefordner, Curve of growth methodology applied to laser-induced plasma emission spectroscopy, Spectrochim. Acta Part B 54 (1999) 491–503. [2] C. Aragón, J. Bengoechea, J.A. Aguilera, Influence of the optical depth on spectral line emission from laser-induced plasmas, Spectrochim. Acta Part B 56 (2001) 619–628.