In situ spectroscopy of Sm(III) and Sm(II) in LiCl–KCl eutectic molten salt

Fiber optic-based Raman and UV–Vis spectroscopy systems were commissioned for use in an inert atmosphere for in situ analysis of high temperature molten salts. The speciation of samarium chloride was studied in the LiCl–KCl eutectic system at 500 °C. Raman and electronic absorption spectra indicated trivalent samarium forms an octahedral SmCl₆³⁻ complex with two detectable Raman features. Metallothermic and electrolytic reduction of Sm(III) to Sm(II) in the alkali halide solution was carried out to investigate the coordination of Sm(II) in the same eutectic salt. Formation of the Sm(II) was confirmed using UV–Vis absorption spectroscopy. The resulting spectra are reported and discussed in terms of complex formation, inelastic scattering, and electronic absorption of the reduced Sm(II) ions. The Raman spectrum of metallothermically produced Sm(II) exhibited similar shift to the Raman spectrum of metallothermically reduced Nd(II).