ZnI ₂ -Mediated Synthesis of High-Purity Rare Earth Iodides with Systematic UV–Vis–NIR Absorption Signatures

byproducts under vacuum, and (iii) two-zone vacuum sublimation to afford highly crystalline, high-purity rare earth iodides. Using this protocol, we obtained 13 rare earth triiodides and the divalent diiodides of Eu and Yb. The high purity of these materials enables systematic UV-vis-NIR diffuse-reflectance spectroscopy under unified synthetic and measurement conditions, allowing comparative analysis of 4f-4f, 4f-5d, and iodide-to-metal charge-transfer absorptions across both diiodides and triiodides.