Soliton in polyacetylene

As pointed out above, the most accurate and reliable information obtained by ENDOR is the resonance frequency that directly gives the hyperfine coupling con.stant. In this respect, the firequency-derivative ENDOR spectra obtained by cw-ENDOR detection by employing the frequency modulation scheme, are particularly important because of high-frequency resolution. Combined with ENDOR-induced ESR, the maximum ENDOR frequency, important in identifying the peak value of the spin density distribution, can be determined very accurately [7]. Specific examples are discussed in the cases of solitons in polyacetylene and polarons in poly(paraphenylene vinylene) in Sections 3.2 and 3.3. 

Table 6.3. Spin density distribution parameters of the soliton in polyacetylene determined from the ENDOR spectra of stretch-oriented ci.t-rich samples at low temperatures with the aid of ENDOR-iiiduced ESR measurements [104]...

Figure 1.3 Bonding structure of a soliton in polyacetylene. The configurations A, to the left, and B, to the right, are equivalent, but there is a defect where they meet. The central carbon atom shares electrons in three a-bonds, but the fourth (n) electron is unpaired. The system is charge-neutral, but has spin V2...

Bally, T, D.A. Hrovat, and W.T. Borden. 2000. Attempts to model neutral solitons in polyacetylene by ah initio and density functional methods. The nature of the spin distribution in polyenyl radicals. Phys Chem Chem Phys 2 3363. 

ESEEM has been applied to the study of surface complexes, coordination of water in metmyoglobin, the structures of ligands in a copper protein, magnetic properties of electronic triplet states, and solitons in polyacetylene. 

FIGURE 2 (a) Polaron in polythiophene, (b) bipolaron in polythiophene, and (c) soliton in polyacetylene. 

If there are mobile charged solitons in polyacetylene (Figure 1.14), it may be expected that they are responsible for the electrical conductivity. If there were samples with very long perfect chains of trans-polyacetylene, then it would be probable that this solitonic charge transport would be observed. If,... 

Solitons in Polyacetylene 1015 Scanning Probe Microscopy 1040 Soft Lithography 1041... 

The analysis of the dielectric increment and the relaxation time in the dielectric relaxation spectra indicates that the HF relaxation is ascribable to a much more localized carrier transport along the polymer chain [175a]. The diffusion constant >h of the HF relaxation was about 2 x 10 m s with the transport range Lh of 50 nm. This Lh corresponds to approx. 100 thiophene rings in length, which may represent the effective size of the 7r-conjugation. Note that the value of Dh is of the same order as the diffusion constant of neutral solitons in polyacetylene determined by NMR [177] and ESR measurements [178] or that of polarons in polyaniline estimated by ESR [179], Thus, the diffusion constant of the MF relaxation... 

Takahashi, A. and Fukutome, H. (1989) "Effects of Dopant Ions on Solitons in Polyacetylene" Synth. Met. 28, D469-D475. 

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