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Laser induced breakdown spectroscopy (LIBS) has been applied to study metallic meteorite fragments. Plasma temperatures around 10,000 K were obtained in focus of the laser beam. Investigations concerning spatial mapping of concentrations regarding nickel in a meteorite has been performed. Several spectroscopic nickel lines were studied. Etched samples of meteorites that clearly show beam-like structures were examined by LIBS.
Atomic emission of laser-induced plasma on etched meteorite samples has been studied for quantitative elemental analysis regarding the nickel content of iron meteorites. When looking at the chemical composition of meteorites an international classification system divides the meteorites into different groups and sub-groups. There are three main groups; stony meteorites, stony-iron meteorites and iron meteorites. The last group consists of two different alloys, kamacite and taenite, that appear in different quantities and structures. Iron meteorites are divided into three groups; octahedrites, hexahedrites and ataxities. In this study, spatial mapping of the concentrations of nickel in iron meteorites were performed and several nickel lines were studied. Especially regions showing beam-like structures of the etched meteorites where examined in detail by applying the LIBS methodology. The kamacite can be identified as broad bands or beam-like structures, whereas the taenite looks like highly reflective thin ribbons. The plasma was created with 8 ns wide pulses using the second-harmonics from a Q-switched Nd:YAG laser. The experiments were performed in air at atmospheric pressure. The plasma emission was detected with temporal resolution, using an Echelle spectrometer with a wide spectral range (300-900 nm) combined with an intensified CCD camera. The spectrometer has and a spectral resolution of R=7500 over the whole spectral range. The plasma temperature was determined applying the Boltzmann plot method, from spectra obtained under optimized experimental conditions. The Ni concentrations of kamacites lies around 4-7.5% and the taenite nickel concentrations range between 27-65%. The meteorite fragments studied were from samples found in Pajala in the northern part of Sweden
By examining both the average concentrations of nickel and concentration differences between the meteorite sections, conclusions can be drawn about the structure and history of the meteorite.
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