Bipolarons

Another material, cited by Schlenker (1985), for which bipolarons probably exist is Na0 3V205. Clear evidence is also given by Klipstein et al (1985) for nonmagnetic charge carriers in polyacetylene. 

As the temperature rises, a second-order phase transition occurs at a temperature TP given by 

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Eig. 2. Lattice distortions associated with the neutral, polaron, and bipolaron states in poly(p-phenylene). 

Figure 7-27 shows the frequency dependency of the in-phase PA bands in a-6T, measured at the maxima of the various PA bands. As expected, the two polaron bands are correlated with one another, having virtually the same dynamics. In contrast, the bipolaron PA band at 1.1 eV is virtually flat from 10 to 1000 Hz, indicating that trapped pol is are longer lived than trapped bipolarons in -6T. The excitation lifetimes modeled by comparing the data in Figure 7-27 to... 

Figure 7-2H. (a) ll-l ADMR and (b) A-PADMR spectra of u-6T film. The peaks of polarons, bipolarons, and triplet cxei-(ons are labeled. 

An alternative interpretation for the activated behavior of the photocurrent and the PIA-decrease with temperature was proposed by Townsend et al. [35], They assigned their experimental results to a thermally activated interchuin-hoppmg mechanism for bipolaron-like charged soliton pairs, the experiments of which were carried out on Durham /ran.v-polyacetylene. 

Figure 2. Radical cations (polarons) and dications (bipolarons) obtained by oxidation of the neutral chain. The rotated angles and counter-ions needed to retain electroneutrality are not shown.

Figure 16. Evolution of the population of the polaronic and bipolaronic bands during polymer oxidation. CB, conducting band, P.B., polaronic band, V.B., valence band, B.P.B., bipolaronic band.

Figure 28. Energetic transitions in neutral and oxidized polaronic and bipolaronic levels. Energy transitions fit UV and visible photons, respectively.

Bi-layer angular movement during current flow, 348, 349, 350 Biological processes, mimicked, 425 Bipolaronic bands as a function of oxidation depth, 342 Bipolar iron-selective film, 226 Bismuth... 

Emersed electrode, 12 Energy scales and electrode potentials, 7 Energy transitions via polaronic and bipolaronic levels, 362 Engineering models, for fluorine generation cells, 539 Esin and Markov plots, 259-260 Experimental data comparison thereof, 149 on potential of zero charge, 56... 

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