Loading effect of matrix compounds in aerosol LIBS measurements

In this work the effect of concomitant mass present in the probe volume on the Cu I LIBS signal in aerosol is studied for a correct interpretation in the quantitative analysis. Mg, Cr and Na are considered as matrix elements and the effect on the emission line is investigated increasing the loading of the elements with respect to copper concentration. Moreover, the role of the specific matrix compounds employed is also analyzed comparing Na chloride and Na acetate. The peak and base of Cu I LIBS signals as well as their corresponding peak/base ratios are detected increasing the concentration of the matrix compounds under analysis. To explore this matrix effect on the plasma, the temporal analysis of the peak and base of the Cu I emission line is performed with and without chromium in the highest concentration under analysis. Finally, temperature measurements are carried out in the different matrix conditions at relatively short delay time considering nitrogen neutral lines. The results obtained highlight the effect of the concomitant mass present in the probe volume, essentially related to the physical properties of the compounds considered. These properties can affect plasma conditions changing the temperature and the plasma temporal evolution, and ultimately affecting the LIBS signal.