Solitons negatively charged soliton

Fig. 4.2 A short segment of t rans -polyacetylene is shown with an abrupt (idealized) reversal of the bond alternation pattern (see text). Top- a neutral soliton with an unpaired spin and an energy state near the middle of the electron energy gap. Middle the addition of an electron results in the formation of a spinless negatively charged soliton. Bottom the extraction of an electron from the top results in the formation of a spinless positive soliton. The optical transitions associated with the charged solitons are indicated as arrows on the right.

With this discussion in mind, we can now examine optical transitions expected for other band structures found in CPs (Fig5 22l9). For neutral, positively and negatively charged solitons such as those found in poly (acetylene), these are illustrated in Fig. 2-19a. For negatively charged polarons and bipolarons, they are illustrated in Figs. 2-19b and 2-19c respectively. 

Figure 5-7. Band diagram of solitons with positively charged, neutral, and negatively charged systems, from left to right.

Figure 13.24 A soliton in franj-polyacetylene. The shaded ellipse in the centre of the soliton may represent either an electron hole (creating a positively charged soliton), a single electron (creating a neutral soliton) or two electrons (creating a negative soliton)...

Figure 3. a. A negative soliton in t/ans-polyacetylene. b. The filled midgap state has no spin and carries a negative charge. 

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