Polydiacetylene types

The polydiacetylene crystals (1-4) most strikingly corroborate these conjectures. Along this line of thought is also shown that this electron-phonon interaction is intimately interwoven with the polymerisation process in these materials and plays a profound role there. We make the conjecture that this occurs through the motion of an unpaired electron in a non-bonding p-orbital dressed with a bending mode and guided by a classical intermolecular mode. Such a polaron type diffusion combined with the theory of non radiative transitions explains the essentials of the spectral characteristics of the materials as well as their polymerisation dynamics. ... 

Fig. 5 /d-Tds characteristics for polydiacetylene monolayers, assembled and polymerized on the air-water interface (inset) and transferred to form bottom-contact, bottom-gate p-type FETs... 

Crystalline polydiacetylenes, exhibiting a fully conjugated backbone, can be obtained [113] by thermal or photochemical polymerization of the monomer R C=C C=C R, where R is the organic substituent. The polymeric structures of the type... 

Transport phenomena were intensely studied for various types of the polydiacetylenes 152-171]. 

I. Is it possible to observe a shift in coherent Raman scattering in the three-level system with A-type coupling We have done an experiment to obtain a femtosecond Raman gain spectrum in polydiacetylenes. The Raman spectrum is shifted to the red under increased pump (to i) intensity. By changing o>2> the amplification peak signal is to be shifted to lower frequency. If the optical Stark effect is observed, then, in principle, it should be possible to observe the effect of a high field on the coherent Raman spectrum (see Fig. 1). 

One is bound to find from time to time unique, specific systems where a special mechanism causes an enhancement of Raman scattering. Such a case, for instance, is probably the enhancement of the Raman scattering of oxygen on polydiacetylene. " It is thought to originate from a charge transfer mechanism. In this review such systems will be considered SERS active only if several molecules (of different types) show an enhancement. 

Type of reaction Polymerization Reaction condition solid-state Keywords diacetylene, polydiacetylene... 

Fig. 2 Polyenes and the 2 state, (a) Schematic representation of the singlet 2Ag state in a polyene, showing its equivalent description either as a triplet-triplet or as soliton-antisoliton pair. Adapted from ref. 33. (b) Polyene-type structures discussed in the text. 1 Polydiacetylene [34,35], 2 Poly(diethyldipropargylmalonate) 136], 3 Poly(3-dodecylthienyl-enevinylene) [37], 4 Polyibenzodithiophene thiophene dioxide) [38]. R-groups denote solubilizing chains, (c) Models of singlet fission in polyenes, mediated by formation of 2Ag (left) or directly from IBu (right).

One of the most notable examples of the application of EA spectroscopy to organic semiconductors is polydiacetylene, in which EA spectroscopy was able to separate absorption bands of quasi-ID excitons from that of the continuum band [78]. The confined excitons were shown to exhibit a quadratic Stark effect, where the EA signal scales with and the EA spectrum is proportional to the derivative of the absorption with respect to the photon energy. In contrast, the EA of the continuum band scales with and showed Frank-Keldish (FK) type oscillation in energy. The separation of the EA contribution of excitons and continuum band was then used to obtain the exciton binding energy in polydiacetylene, which was found to be -0.5 eV [78]. 

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