Original paper

In-situ analysis of nitrogen in minerals

Bastoul, Abdel Majid; Pironon, Jacques; Mosbah, Michelle; Dubois, Michel; Cuney, Michel

European Journal of Mineralogy Volume 5 Number 2 (1993), p. 233 - 244

54 references

published: Apr 27, 1993
manuscript accepted: Dec 14, 1992
manuscript received: Oct 2, 1992

DOI: 10.1127/ejm/5/2/0233

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Abstract

Abstract In-situ analysis of nitrogen content in silicate minerals represents an important tool for the understanding of the paragenetic relations in rocks. Three microscopic techniques are applied to the in-situ analysis of nitrogen trapped as ammonium ions in silicate minerals (muscovite, biotite, feldspar) from the metamorphic schists of the Jebilet series (Morocco) and Cévennes (France). 1) Spectra obtained with Fourier transform infrared microspectroscopy show vibrational vi, V2, V3 bands and some overtone and combinations of the ammonium molecule. The quantitative analysis is disturbed by dichroism effects, and needs the use of natural or synthetic silicate standards. The ammonium ion of the analysed sheet minerals is not detected by Raman microspectroscopy. 2) The nuclear microprobe is applied on the same mineral preparation and nitrogen content is measured using the 14N(d,αo)12C and 14N(d,po)15N nuclear reactions with a deuteron energy of 1.8 MeV. TiN is used for calibration; concentrations from 360 to 2200 ppm are obtained. 3) The ion microprobe has similar application fields as the nuclear microprobe, but is more sensitive to matrix effects. The isotopic composition cannot be obtained considering the sensitivity of these techniques to the low 15N content of minerals (near 1 to 10 ppm). The detection limit lies between 10 and 100 ppm, and is similar to the detection limits of the bulk techniques

Keywords

NF4+-ionin-situ analysisFT-IR microspectroscopynuclear microprobeion microprobe