EXAFS and Near Edge Structure IV

J. Phys. Colloques 47 (1986) C8-615-C8-618
DOI: 10.1051/jphyscol:19868115

POLARIZED EXAFS AND NEAR-EDGE SPECTRA OF HALOGEN-DOPED POLYACETYLENE

H. OYANAGI¹, M. TOKUMOTO¹, T. ISHIGURO¹, H. SHIRAKAWA², H. NEMOTO², T. MATSUSHITA³ et H. KURODA<sup>4

1</sup>  Electrochemical Laboratory, Sakuramura, Niiharigun, Ibaraki 305, Japan
²  Institute of Materials Science, University of Tsukuba, Sakuramura, Niiharigun, Ibaraki 305, Japan
³  National Laboratory for High Energy Physics, Ohomachi, Tsukubagun, Ibaraki 305, Japan
⁴  Department of Chemistry and Research Center for Spectrochemistry, The University of Tokyo, Hongo, Bunkyoku, Tokyo 113, Japan

Abstract
Polarized EXAFS and near-edge spectra were measured for (CHBr_y)_x and (CHI_y)_x on the Br K- and I L-edges over a wide range of dopant concentration. The analysis of EXAFS and near-edge spectra indicates that, in the lightly doped region (0.01< y < 0.2), polybromine ions highly oriented along the c-axis are formed while bromines also form covalent bonds with polyacetylene chain which increases in number on going to heavily doped region (y > 0.2). Bromines are incorporated as isolated ions in the early stage of doping (y < 0.01). In (CHI_y)_x, iodines form linear polyions which are chemically less reactive. The difference in the magnitude and dopant concentration dependence of electrical conductivity between bromine and iodine doping is ascribed to the degree of termination of conjugated chains by an addition reaction of halogens.