Frenkel exciton model of optical absorption and photoluminescence in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>α</mml:mi></mml:math>-PTCDA

Vragović, I.; Scholz, Reinhard

doi:10.1103/physrevb.68.155202

Cited by 76 publications

(77 citation statements)

References 39 publications

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“…A more detailed investigation on temperature-dependent absorption in PTCDA films 37 as well as a discussion about other absorption models will be given elsewhere. 38,39 For a better comparison, the two PL spectra and the absorption spectrum are slightly offset to each other. No significant changes in the PL spectrum are observed as the excitation energy is changed from 2.84 eV on the highenergy side of the -* absorption to 2.33 eV closer to the narrow 0-0 exciton absorption band.…”

Section: Resultsmentioning

confidence: 99%

Exciton emission in PTCDA films andPTCDA∕Alq3multilayers

2004

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We investigate the exciton emission in 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) thin films and PTCDA/aluminium-tris-hydroxyqinoline ͑Alq 3 ͒ multilayers by photoluminescence spectroscopy in the temperature range from 10 to 300 K. The films are grown by organic molecular beam deposition on Si (001) and Pyrex™ substrates at high vacuum. The obtained temperature dependence of the different recombination channels arising from indirect Frenkel excitons, charge transfer excitons, excimers, and relaxed excited monomers is compared to the recombination channels in single PTCDA crystals. A strong recombination band is observed at 1.63 eV in PTCDA/ Alq 3 multilayers. This emission band is attributed to charge transfer transitions between stacked PTCDA molecules that are compressed by strain fields within the PTCDA layers. This assignment is supported by strain-dependent photoluminescence measurements on pure PTCDA films.

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Section: Resultsmentioning

confidence: 99%

Exciton emission in PTCDA films andPTCDA∕Alq3multilayers

2004

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“…[142] is just one example of recent experiments probing quench dynamics similar to that considered here. The models are also important for molecular aggregates [143][144][145] and energy transport in large organic and biomolecules [146][147][148][149][150][151]. Experiments in many of these systems have measured the same or closely related quench dynamics to that considered herein.…”

Section: Physical Realizationsmentioning

confidence: 98%

Quantum correlations and entanglement in far-from-equilibrium spin systems

et al. 2014

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By applying complementary analytic and numerical methods, we investigate the dynamics of spin-1/2 XXZ models with variable-range interactions in arbitrary dimensions. The dynamics we consider is initiated from uncorrelated states that are easily prepared in experiments, and can be equivalently viewed as either Ramsey spectroscopy or a quantum quench. Our primary focus is the dynamical emergence of correlations and entanglement in these far-from-equilibrium interacting quantum systems: we characterize these correlations by the entanglement entropy, concurrence, and squeezing, which are inequivalent measures of entanglement corresponding to different quantum resources. In one spatial dimension, we show that the time evolution of correlation functions manifests a non-perturbative dynamic singularity. This singularity is characterized by a universal power-law exponent that is insensitive to small perturbations. Explicit realizations of these models in current experiments using polar molecules, trapped ions, Rydberg atoms, magnetic atoms, and alkaline-earth and alkali atoms in optical lattices, along with the relative merits and limitations of these different systems, are discussed.

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“…Molecular interactions inside the crystal are often approximated to be (screened) interactions between point-dipoles located at the centre of mass of each molecule and corresponding to the dipole moment of the molecular transition. Such an approximation fails for molecules close to each other compared to their dimensions and it can be improved by using the transition charge distribution method, which consists in www.intechopen.com approximating the delocalized molecular transition dipole with a distribution of point charges located at atomic positions (Alessandrini et al 2011, Markovitsi et al 1995, Scholz et al 2000, Vragovic & Scholz 2003). An even more accurate estimate of the molecular interactions can be obtained by quantum mechanical calculations involving several molecules, but such a refinement would be relevant only for nearest-neighbour or nextnearest-neighbour molecules and, in our test cases, would only slightly correct the absorption spectra.…”

Section: Melt Growthmentioning

confidence: 99%