Energy levels of Ho3+ in HoCl 3–6

Abstract

The ⁵S₂, ⁵F₄, ⁵F₂, ³K₈, ⁵G₆, ⁵F₁, ⁵G₅â†�⁵I₈ absorption spectra of Cs₂NaHoCl₆ have been recorded at temperatures down to that of liquid helium and new assignments are made for the ⁵S₂, ⁵F₄, ³K₈ and ⁵G₅ terms of HoCl^3–₆. The ⁵F₃→⁵I₈; ⁵F₄, ⁵S₂→⁵I₇, ⁵I₈ and ⁵F₅→⁵I₇ luminescence transitions of HoCl^3–₆ in various elpasolite lattices are reported and assigned, together with luminescence decay measurements. Including the previously reported data, these results enable 57 of the first 60 crystal-field levels of HoCl^3–₆, comprising 14 L_J terms, to be firmly assigned and tentative assignments are made for the remaining three levels. The agreement between the calculated and observed crystal-field splittings is reasonable.