Structural study of two reactive diacetylenes

Spagnoli, S.; Schott, M.; Johnson, Mark; Toupet, Loı̈c

doi:10.1016/j.chemphys.2007.02.007

Cited by 18 publications

(44 citation statements)

References 43 publications

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“…The two processes can be seen at play in the blue chains of poly-3BCMU and poly-4BCMU [5]. In the former there is almost no change in repeat unit distance between 300 and 15 K [34]so the change in |D| dominates. The resulting decrease in exciton transition energy is -50 meV.…”

Section: B Temperature Shift Of Transitionsmentioning

confidence: 99%

“…To understand the relationship between conformation and electronic structure in PDA, a better knowledge of electronic properties of non planar chains is needed, also providing new experimental data to be compared with further theoretical studies. Obtaining high quality isolated chains dispersed in their monomer single crystal is less demanding than obtaining a perfect completely polymerized PDA crystal: for instance poly-4BCMU and poly-3BCMU chains in their monomer crystal are high quality quantum wires, whereas the 4BCMU crystal becomes disordered around a polymer concentration of 10% in weight [33,34] and 3BCMU crystals do not even polymerize completely [35]. Yet, absorption spectra of chains in crystals with low polymer content are often not well resolved.…”

Section: Introductionmentioning

confidence: 99%

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Twisted polydiacetylene quantum wire: Influence of conformation on excitons in polymeric quasi-one-dimensional systems

et al. 2010

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Highly luminescent isolated polydiacetylene (PDA) chains in a new diacetylene crystal are studied. The diacetylene crystal structure and theoretical calculations suggest that the chains are not planar and more strongly twisted than any known PDA. Yet the chains behave as quasi perfect quantum wires, showing that this behaviour is generic among PDA, provided crystal order is high enough. The exciton energy, E 0 , is higher than in any other well ordered PDA providing a relationship between E 0 and twist angle. On the other hand the exciton binding energy and Bohr radius are significantly affected as demonstrated in electroabsorption experiments (and developed in a companion paper).

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Section: B Temperature Shift Of Transitionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Twisted polydiacetylene quantum wire: Influence of conformation on excitons in polymeric quasi-one-dimensional systems

et al. 2010

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“…of lateral size of a few mm 2 were grown in the dark at 40 C from a saturated solution of purified powder in acetone. A fraction of molecules of density N 0 1:52 10 21 cm ÿ3 in the monoclinic crystal [14,15] is transformed into conjugated chains which run parallel to the symmetry axis b creating excitons with transition dipole k b and an absorption constant of 10 6 cm ÿ1 at room temperature in fully polymerized samples [16]. Since the surface of the crystal platelets contains the b axis normal incidence of b-polarized light generates always a transverse propagating mode.…”

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confidence: 99%

Polariton Induced Transparency at Low Light Level: Polymer Chains Dispersed in a Monomer Single Crystal

Weiser

Berréhar

2007

Phys. Rev. Lett.

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Excitons of polydiacetylene chains, diluted in a 3BCMU monomer single crystal, turn at very low light intensity into a nonabsorbing polariton state once the polymer concentration exceeds 10{-4} in weight. The transition is evident from a Lorentzian absorption peak which is truncated at an optical density OD approximately 2 and is consistent with polariton coupling of light to eigenstates of the solid while Rabi coupling of individual chains to light is excluded. The saturated absorption is nearly independent of polymer content and crystal thickness and defines a surface region where photons are converted into polaritons, the corresponding electromagnetic eigenmodes of matter.

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“…Basically, this is a smart extension to the familiar rigid-body constraints and has been adopted with classical methods for large organic molecules following a phase transition [1] and for oxygen atoms positions in a metal oxide structure with vacancies [2]. In the latter case, using DFT, a few subsequent cycles of Rietveld refinement provided the final structure.…”

Section: Examplesmentioning

confidence: 99%