Electronic absorption spectra of lanthanides in a molten chloride

Electronic absorption spectra of trivalent samarium, dysprosium, holmium, and erbium in LiCl–KCl eutectic, NaCl–2CsCl eutectic, and mixtures of LiCl and CsCl were measured. The oscillator strength of their hypersensitive transitions was evaluated, which showed clear temperature dependence. This temperature dependence suggests that the octahedral symmetry of the LnCl ₆ ³⁻ complex (Ln: Sm, Dy, Ho, or Er) is distorted with increasing temperature. For mixtures of LiCl and CsCl, the oscillator strength indicated that the octahedral symmetry of the LnCl ₆ ³⁻ complex is distorted at high LiCl content and the distortion proceeds with increasing the LiCl content.