Band edge and neutral soliton absorption in polyacetylene: The role of Coulomb correlation.
01 January 1985
The technique of Photothermal Deflection Spectroscopy (PDS) has provided the clearest measurement of the absorption edge in polyacetylene. Compensated trans-(CH)(x) has an Urbach edge which covers orders of magnitude change in absorption in the range 0.9-1.7 eV. Parallel measurements of PDS and spin resonance on compensated trans-(CH)(x) fails to reveal the predicted neutral soliton (S(o)) absorption near midgap. The S(o) absorption has been measured in a Photoinduced Absorption (PA) experiment in which the PA spectrum is dominated by a change in the number of S(o) centers. These results provide new insight into fundamental issues as the importance of Coulomb correlations and the role of disorder in polyacetylene.