XPS Studies of PtCl4 and H2PtCl6·6H2O doped polyacetylene

The PtCland HPtCl·6HO doped polyacetylene were studied by X-ray photoelectronspectroscopy and transmission electron microscopy.We found that both Pt 4f and Cl 2p peaks couldbe resolved into two components both with a splitting of ca.1.5 eV.The higher binding energycomponents of Pt 4f peak is attributed to Ptand the lower binding energy one to Ptspecies.Fromquantitative analysis of the results of decomposition of both Pt 4f and Cl 2p peaks it was found thatan atomic ratio of chlorine to platinum for Ptspecies is（Cl）/（Pt）2 and that for Ptspeciesis （Cl）/（Pt）6 for both PtCland HPtCl·6HO doped polyacetylene.The C 1s peaks could bedecomposed into two components separated by ca.1 eV.The intensity of the higher binding energycomponent increased with increasing dopant concentration.These indicate that the platinum saltdoping proceeds through charge transfer from polyacetylene chain to platinum atom resulting ina partial reduction from Ptto Ptstate.The existence of PtClcluster on the surface of the dopedpolyacetylene film was supported by transmission electron microscopy and electron diffraction obser-vations.These results indicate that a random distribution of the dopant along the macromolecularchain,and the charge per carbon atom in the metallic region of doped polyacetylene has been estimatedto be 0.2|e|.From these results the mechanism of the PtCland HPtCl·6HO doping process inpolyacetylene is clarified as follows:2PtCl+2e——PtCl+PtClfor PtCldoping;2HPtCl+2e——PtCl+PtCl+4HCl for HPtCl·6HO doping.Thus the dopant anion in polyacetylene is PtClfor both PtCland HPtCl·6HO doping.