Atomic Effects In EXAFS Structural Analysis of Redox I^-/I₃^- Solid State Electrolytes

 Jana Padežnik Gomilšek^a, Iztok Arčon^b,c and Alojz Kodre^d,c

^aFaculty of Mechanical Engineering, Smetanova 17, SI-2000 Maribor, Slovenia
^bPolytechnic Nova Gorica,Vipavska 13, SI-5000 Nova Gorica, Slovenia
^cInstitute Jožef Stefan, Jamova 39, SI-1000 Ljubljana, Slovenia
^dFaculty of Mathematics and Physics, Jadranska 19, SI-1000 Ljubljana, Slovenia

Absrtract
A highly disordered iodine neighborhood in silica-based nanocomposite redox I^-/I₃^- electrolytes produces a weak EXAFS (Extended X-Ray Absorption Fine Structure) signal at the iodine K-edge. The signal is comparable in amplitude to sharp features arising from intra-atomic effects, the multielectron photoexcitations of the iodine atom. Using pure atomic absorption of neighbor elements, structural and atomic components of the signal are separated and characterized. The iodine atomic absorption background is transferable to EXAFS spectra of other iodine compounds and can be used to minimize systematic error of background removal in structural analysis. The spectral features of the iodine atomic absorption background are found to follow smoothly the trends exhibited by data on the two subsequent elements Xe and Cs.

Key words: EXAFS, multielectron photoexcitations, iodine K-edge.