Analysis of acid pitchstone (Iceland) using laser induced breakdown spectroscopy (LIBS)

Abstract

Analysis of acid pitchstone (sample from Iceland) using laser induced breakdown spectroscopy (LIBS) is presented in this study. The rock sample was taken because of its uniform composition and a homogenous structure at microscale. Elements like Si, Fe, Ca, Mg, Al, Mn, Ti, Na, K, Ba, Sr and Li were detected in the LIBS spectra. Important plasma parameters (electron density and temperature) were calculated on the base of Stark broadening mechanism of spectral lines and Saha- Boltzmann plot method, respectively. Quantitative analysis was performed using calibration free (CF) approach of LIBS method. CF-LIBS analysis compared to reconstructed bulk rock analysis using precise mineral and glass analyses obtained by electron microprobe analysis (EMPA) gives a good correlation, sufficient enough for having primary information of chemical composition of the studied rock sample or alternatively large mineral phases. An element with very low atomic number, lithium, was detected only by LIBS. Li is not detectable on microprobe. Taking into account possible local mineral accumulations and imprecisions induced by estimation of mineral volumes in the glass the CF-LIBS method gives acceptably precise analyses for geological purposes.

Keywords

• Laser Induced Breakdown Spectroscopy
• LIBS
• plasma parameters
• acid pitchstone