PHOTOINDUCED ABSORPTION IN $EMERALDINE^{\ast}$

We report the photoinduced absorption spectrum of the emeraldine base form (EB) of polyaniline, a polymer consisting of phenyl and quinoid rings in a ratio of 3:1 linked by amine or imine nitrogen atoms. When pumped by laser photons of energy 2.0-2.7 eV, EB exhibits a photoinduced bleaching band which peaks at 1.8eV, as well as two correlated photoinduced absorption bands which peak at $∼1.3 e V$ and 3.0eV. Laser power and chopping frequency dependences of the 1.3eV and 3.0 eV photoinduced absorption bands are nearly identical and differ significantly from those of the 1.8 eV photoinduced bleaching band. The results are compared to a model of photoexcitation of a 2 eV molecular exciton band1 and formation of positive and negative polarons. We will also discuss the photoinduced absorption spectrum of electrically conducting protonated emeraldine.

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$*$ This work supported in part by the Defense Advanced Research Projects Agency through a grant monitored by the U.S. Office of Naval Research. $1$ C.B. Duke, E.M. Conwell, and A. Paton, Chem. Phys. Lett 131, 82 (1986)

Author Institution: Department of Physics, The Ohio State University; Department of Physics and Department of Chemistry, The Ohio State University; Department of Chemistry, University of Pennsylvania

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http://hdl.handle.net/1811/17320

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Abstracts of OSU International Symposium on Molecular Spectroscopy 1980-1989

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