Determination of elemental concentrations in underwater LIBS plasmas using spectral simulation for copper–zinc alloys

Abstract

The analysis of double-pulse LIBS plasmas is a promising technique for environmental neutral underwater material exploration. Since the required spectral analysis methods or suitable calibration curves have barely been investigated for deep-sea applications, a method for spectral simulation and evaluation was developed, enabling evaluation of the elemental concentrations even under non-atmospheric conditions. For this, a method for spectral simulation and evaluation was created, containing the simulation of spectra resulting from multi-elemental plasmas, calculation of data sets with spectral characteristics for various plasma pressures, temperatures and elemental concentrations and the estimation of the plasma parameters and the elemental concentrations related to the measured spectra. Then the accuracy was examined depending on different external parameters, such as laser pulse energy and water pressure. Finally, it was shown that a calibration curve routine for copper–zinc alloys could be created with a mean deviation of 3 at% independent of the laser setup. Furthermore, it was shown that this method for spectral simulation and evaluation is suitable to evaluate LIBS spectra for up to 60 MPa hydrostatic water pressure.