INSITU ELECTRON-SPIN RESONANCE EXPERIMENTS ON POLYACETYLENE DURING ELECTROCHEMICAL DOPING

We present results obtained from in situ e. s. r. measurements on both n-type and p-type materials during electrochemical doping. For the n-type data were obtained over an extended concentration range out to about 15 mol% (or well into the metallic regime); for p-type left bracket left bracket (CH)** plus **y(ClO//4** minus )//y right bracket //x we have succeeded in achieving doping levels sufficiently high in situ to observe the abrupt first-order onset of the Pauli spin susceptibility. Comparison of the results obtained from p-type and n-type electrochemical doping shows remarkable similarities between the two. The precise symmetry of the results obtained from n-type and p-type doping demonstrates without ambiguity the charge conjugation symmetry of trans-(Ch)//x. The mechanism for the first-order electronic phase transition is discussed.