Amplitude and phase modes in<i>trans</i>-polyacetylene: Resonant Raman scattering and induced infrared activity

Ehrenfreund, E.; Vardeny, Z. Valy; Brafman, O.; Horovitz, Baruch

doi:10.1103/physrevb.36.1535

Cited by 335 publications

(220 citation statements)

References 55 publications

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“…5. The mechanism giving 'massive' charge displacements for solitons 37,38 and for polarons [20][21][22]39 is pictorially described in Fig. 5, and may resemble 'the changes in electronic structures induced by specific vibrations' mentioned by Sakamoto et al 4 Figure 5 gives us a picture of polarons as objects that are not static.…”

Section: Discussionmentioning

confidence: 99%

“…For F 5 À , these are vibrations transforming with B representations in C2 symmetry. These vibrational motions drive the polaron along the long axis of the conjugated molecule generating large dipole moments as discussed earlier for charged solitons and polarons 18,[20][21][22][37][38][39] . The present findings indicate that polarons in conjugated chains are dynamic, undergoing changes of charge density driven by molecular vibrations.…”

Section: Discussionmentioning

confidence: 99%

“…The fact that large CH bands are observed despite weak expected and computed dipole derivatives might be understood on the basis of enhanced IR intensities due to vibronic coupling 4,17,20,24,25,39 to low-energy electronic excited states. Nafie's 25 description for the transition dipole of an IR band at frequency o a multiplies the contributions of dipole ARTICLE derivatives to transition moments by a term…”

Section: Discussionmentioning

confidence: 99%

“…This behaviour and related anti-resonances 20 can be understood in terms of amplitude theory 18,[20][21][22]39 or the theory of Nafie 25 , which predicts intensity enhancement from a larger positive dipole matrix element when the low-lying electronic state is above the vibrational excited state (o eg 0 4o a ) but a negative matrix element when o eg 0 oo a . If both occur simultaneously, interference (cancellation) can occur, but simultaneity is important because, as Nafie notes, the dipole strength is the 'absolute square of the electric-dipole transition moment, always a positive quantity.'…”

Section: Discussionmentioning

confidence: 99%

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Giant infrared absorption bands of electrons and holes in conjugated molecules

et al. 2013

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Infrared (IR) absorption bands often convey identifying information about molecules, but are usually weak, having molar absorption coefficients o200 M À 1 cm À 1 . Here we report observation of radical anions and cations of conjugated oligomers and polymers of fluorene and thiophene that possess intense mid-infrared absorption coefficients as large as 50,000 M À 1 cm À 1 , perhaps the largest known for molecular species. For anions of fluorene oligomers, F n , n ¼ 2-4, IR intensities increase almost linearly with n, but with a slope much larger than one, indicating that the absorptions are not extensive properties. Large intensities seem to arise from a mechanism known for charged solitons and polarons in conjugated polymers. In this mechanism, vibrations of ungerade symmetry drive substantial displacements of charge, creating the large dipole derivatives responsible for intense IR absorption. Both experiments and calculations find that pairing with counter-ions attenuates IR band intensities. The IR bands may be diagnostic for bound ion pairs and their escape to form free ions.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Giant infrared absorption bands of electrons and holes in conjugated molecules

et al. 2013

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“…[66][67][68][69][70] In this field, Raman spectroscopy certainly plays a major role (see for instance ref. [71][72][73][74][75] and references therein).…”

Section: The Ideal Infinite Wire: Interplay Between Electronic and VImentioning

confidence: 99%

Carbon-atom wires: 1-D systems with tunable properties

et al. 2016

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This review provides a discussion of the current state of research on linear carbon structures and related materials based on sp-hybridization of carbon atoms ( polyynes and cumulenes). We show that such systems have widely tunable properties and thus represent an intriguing and mostly unexplored field for both fundamental and applied sciences. We discuss the rich interplay between the structural, vibrational, and electronic properties focusing on recent advances and the future perspectives of carbon-atom wires and novel hybrid sp-sp 2 -carbon architectures.

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Vibrational Spectroscopy of Conducting Polymers

Furukawa¹

2001

Handbook of Vibrational Spectroscopy

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The sections in this article are Introduction Infrared and R aman Spectra of Pristine Polymers R aman Spectra of Doped Polymers Doped Polyacetylene Doped Polythiophene Doped Poly( p ‐Phenylene) Doped Poly( p ‐Phenylenevinylene) Doping‐ and Photo‐Induced Infrared Absorption Infrared Spectra of Injected Carriers Concluding Remarks

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Amplitude and phase modes intrans-polyacetylene: Resonant Raman scattering and induced infrared activity

Cited by 335 publications

References 55 publications

Giant infrared absorption bands of electrons and holes in conjugated molecules

Giant infrared absorption bands of electrons and holes in conjugated molecules

Carbon-atom wires: 1-D systems with tunable properties

Vibrational Spectroscopy of Conducting Polymers

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