“…16,17 Only in the past decade, however, measurements have been reported using the HL-band of adsorbed iodine to probe the donor strength of zeolites and other inorganic oxides, such as MgO, γ-alumina, and mesoporous silica. 18,19 It has to be remarked that solids exposing strong electronrich sites are able to cause the dissociation of a pair of I 2 molecules into I + and I 3 -ions, 19 by stabilizing the cation I + , not visible in the UV-visible spectrum, so that only the triiodide anion is revealed. This process, which does not involve any electron transfer from the solid, is also well-known in the case of liquid phase interaction.…”