Short-Range Order Full Multiple Scattering Approach to the Polarized Iodine L1-Edge XANES of IBr Doped in trans-Polyacetylene

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Abstract
In this work, iodine L 1 -XANES of (CH(IBr) y ) x excited by two linearly polarized X-ray are analyzed by use of the short-range order full multiple scattering calculations. The XANES analysis for E ⊥ c polarization (normal to the chain axis) gives us the information on the I–C correlation. One useful information obtained here is that the nearest I–C distance is longer than the sum of the van der Waals radii of I and C. This result can explain the increase of the anisotropy of the electric conductivity by IBr doping. Our XANES analyses can also predict charge distribution on polyanions I 2 Br - as q 1 =-0.5∼-0.7, q 2 =0.2∼0.3 and q 3 =-0.5∼-0.7, where I ( q 1 ) I ( q 2 ) Br ( q 3 ) , q 1 + q 2 + q 3 =-1. The observed sharp peak in E // c XANES is found to be due to the absorption by the end iodine atom.