XAFS analysis of triiodide ion in solutions

Abstract

Iodine K-edge XAFS of triiodide ions in various solvents were measured at SPring-8 BL01B1 and analyzed. Though the anion takes a linear and symmetric form, the second peak expected from enhanced multiple scatterings can be hardly observed because of its large vibrations. The bond distances and the Debye-Waller factors for the I-I couple vary when protic solvents were used and they were similar when aprotic solvents were used. It was indicated that the larger the Mayers' acceptor number of the solvent is, the larger the Debye-Waller factor is. It was also found that among the aprotic solvents, the larger the Gutmann's donor number is, the smaller the Debye-Waller factor is.

Promoting Effect of Layered Titanium Phosphate on the Electrochemical and Photovoltaic Performance of Dye-Sensitized Solar Cells

“…Similar result was reported for layered montmorillonite, which was intercalated by Emim + cations through the ion exchange reaction [24]. It was reported that I 3 − ions in the solution take symmetrical linear form, with a diameter of about 2.9 Å and a length of about 5.8 Å, respectively [25]. For pristine α-TiP, the diameter of zeolite type cavities between the sandwiches is around 2.6Å [15], which is small for I 3 − to transport through the interspace between the sandwiches of α-TiP.…”

Investigation of low cost carbonaceous materials for application as counter electrode in dye-sensitized solar cells

“…By mixing the graphite powder with high surface area carbon blacks such as Vulcan and Ketjen Black, the performance decreased compared to pure graphite. This could be due to the high presence of micro pores in the carbon blacks that are not accessible for the I 3 -reactant [23]. The mixtures of graphite with Ketjen Black or Vulcan show a similar cumulative pore volume, which is about twice that observed for the mixture of graphite and Acetylene Black (Fig.…”

Topical Review: Molecular reaction and solvation visualized by time-resolved X-ray solution scattering: Structure, dynamics, and their solvent dependence

“…Extended X-ray absorption fine structure (EXAFS) technique can serve as an appropriate tool for revealing the structure parameters of the solute, which is usually minor species outnumbered by the solvent. Indeed the structure of the I 3 – ion was also studied by K edge EXAFS, and the study found that the peak corresponding to I–I bond distance of ∼3 Å broadens in protic solvents 95 . However, the broadening was attributed to high Debye-Waller (DW) factor, not to the symmetry breaking caused by solvent-solute interaction.…”