Mini-Excitons and Lattice Dynamics in Mixed CT-Crystals: An ESR, Optical and Raman Spectroscopical Study

Erdle, E.; Möhwald, Helmuth

doi:10.1515/zna-1980-0211

Cited by 8 publications

(4 citation statements)

References 17 publications

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“…The concentration of A in the samples, x, was determined during execution of the structure refinement procedure. Contrary to the previous announcements, 18,19 we noticed a significant difference between the A concentration in the solution and its estimated value in the crystals. In particular, the crystals grown from the same solution of x sol у0.50 exhibited a large variety of A content.…”

Section: Methodscontrasting

confidence: 99%

“…It is known that A-TCNB forms solid solutions with Ph-TCNB in a whole range of concentrations. 18,19 An interesting aspect of the study is, that Ph molecules, taking two different orientations at random, forms a molecular glasslike material. In the studies of the mixed crystals, we are dealing with the problem of local stress introduced by substitutional and orientational disorder.…”

Section: Introductionmentioning

confidence: 99%

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Structure, disorder, and phase transition in ternary crystals of anthracene, phenanthrene, and tetracyanobenzene, AxPh1−xTCNB

Jacques

Rohleder

Mierzejewski

et al. 1995

The Journal of Chemical Physics

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Articles you may be interested inInfluence of anthracene doping on the order-disorder phase transition in phenanthrene AIP Conf. Proc. 1512, 44 (2013); 10.1063/1.4790902 Anisotropic displacive to order-disorder crossover of the orientational phase transition in anthracene tetracyanobenzene crystal J. Chem. Phys. 90, 7346 (1989); 10.1063/1.456214Static disorder in crystals of the anthracene-tetracyanobenzene charge transfer complex Phase transition effects: A crystallographic characterization of the temperature dependency of the crystal structure of the 1:1 charge transfer complex between anthracene and tetracyanobenzene in the temperature range 297 to 119 K The structure of ternary, charge-transfer crystals of anthracene, phenanthrene, and tetracyanobenzene, A x Ph 1Ϫx TCNB, in a wide range of concentrations has been studied. We have focused on the problem of substitutional and orientational disorder of anthracene and phenanthrene molecules and its influence on the orientational instability. The crystal structure determination has been performed at room temperature and 120 K, and the refinement procedures allowed us to determine the orientational disorder for different concentrations. The phase diagram for the orientational phase transition with symmetry change, C2/m to P2 1 /a, has been determined and a critical concentration (x c ϭ0.74) was found. The disorder and the phase diagram has been successfully modeled by a minimization of the crystal energy using the ''split molecule'' concept and the virtual crystal approximation to mimic both orientational and substitutional disorders. The ternary crystals, their structure, disorder, and phase transitions are well understood in terms of a competition between orientational disorder of anthracene molecules and local stresses created by the substitutional disorder ͑with statistical orientations͒ of phenanthrene molecules. A possibility for an existence of molecular orientational glassy state is suggested for concentrations below the critical one.

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Section: Methodscontrasting

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Structure, disorder, and phase transition in ternary crystals of anthracene, phenanthrene, and tetracyanobenzene, AxPh1−xTCNB

Jacques

Rohleder

Mierzejewski

et al. 1995

The Journal of Chemical Physics

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“…Doping of TGS crystals with CA leads to the loss of translational symmetry in TGS:CA solid solutions. For this reason, one would expect a noticeable broadening of the lines in TGS:CA Raman spectrum [66]. However, no significant difference in line widths in Figure 5a,b is observed.…”

Section: Raman Spectroscopymentioning

confidence: 86%

Croconic Acid Doped Triglycine Sulfate: Crystal Structure, UV-Vis, FTIR, Raman, Photoluminescence Spectroscopy, and Dielectric Properties

et al. 2022

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Triglycine sulfate (TGS) single crystals doped with croconic acid (CA) were grown by evaporation from aqueous solutions. X-ray diffraction analysis shows a slight reduction in unit cell volume in TGS:CA compared to pure TGS crystals. The polarized Raman and near-infrared absorption spectra show that the positions of most lines resulting from inter- and intramolecular vibrations are in good agreement with those in spectra of undoped TGS crystals. The inclusion of CA in TGS is confirmed by the presence of bands characteristic of CA in the infrared-Fourier transform spectra. The ultraviolet-visible absorption spectra of TGS:CA are characterized by the presence of additional absorption bands (compared to the spectra of pure TGS) located in the transparent region of pure TGS. In the photon energy region 1.6–3.6 eV, a strong “green” luminescence band is present in TGS:CA upon excitation at λ = 325 nm. The position of the emission band depends on the wavelength of the exciting light. Doping of TGS with CA causes pinning of domain walls, which is accompanied by a decrease in amplitude and frequency dispersion of the dielectric anomaly at the phase transition, a decrease in the switchable polarization and an increase in the coercive field of hysteresis loops.

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“…This allows the study of niiniexcitons, the diffusion range of which is varied by the anthracene concentration c . The present investigation was prompted by the experimental finding that the width of the ESR lines observed in mixed systems increases with decreasing anthracene concentration c [8]. This is explained by the limited size of domains over which the exciton is delocalized taking into account the dimensionality of these domains.…”

Section: Introduction and Description Of The Systemmentioning

confidence: 94%

Statistical Model and Experiments on Low‐Dimensional Exciton Transport

Erdle

Möhwald

1980

Physica Status Solidi (b)

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A statistical model is presented to calculate the concentration dependence of the ESR line width of triplct excitons in mixed CT crystals. A comparison between computation and experiments yields the anisotropy of energy diffusion. As experimental example data on the cha,rge-transfer crystal anthracenec-phenanthrenel -,-TCNB (0 5 c 5 1) are presented. It is shown that triplet excitons move by a factor of 15 to 60 faster along one distinct direction than perpendicular to it.Es wird ein statistisches Modell zur Berechnung der Konzentrationsabhangigkeit der ESR-Linienbreit.e von Triplett-Exzitonen in CT-Mischkristallen angegehen. Der Vergleich zwischen Rechnung und Experimentcn liefert die Anisotropie der Energiediffusion. Als experimentelles Beispiel werden Werte des Ladungstransferkristalls Anthrazen,-Phenantrenl -,-TCNB (0 5 c 5 1) mitgeteilt,.Es wird gezeigt, da8 sich Triplett-Exzitonen um einen Faktor 15 bis 60 schneller in einer bestimmten Richtung bewegen, als senkrecht dazu.

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Mini-Excitons and Lattice Dynamics in Mixed CT-Crystals: An ESR, Optical and Raman Spectroscopical Study

Cited by 8 publications

References 17 publications

Structure, disorder, and phase transition in ternary crystals of anthracene, phenanthrene, and tetracyanobenzene, AxPh1−xTCNB

Structure, disorder, and phase transition in ternary crystals of anthracene, phenanthrene, and tetracyanobenzene, AxPh1−xTCNB

Croconic Acid Doped Triglycine Sulfate: Crystal Structure, UV-Vis, FTIR, Raman, Photoluminescence Spectroscopy, and Dielectric Properties

Statistical Model and Experiments on Low‐Dimensional Exciton Transport

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