Frenkel and Charge Transfer Excitons in Quasi-one-dimensional Molecular Crystals with Strong Intermolecular Orbital Overlap PDF Download
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Author: Michael Hoffmann
Publisher:
ISBN:
Category :
Languages : en
Pages : 147
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Author: Michael Hoffmann
Publisher:
ISBN:
Category :
Languages : en
Pages : 147
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
We present a theoretical and experimental study on the lowest electronically excited states in quasi-one-dimensional molecular crystals. The specific calculations and the experiments are performed for the model compounds MePTCDI (N-N'-dimethylperylene-3,4:9,10-dicarboximide) and TCDA(3,4:9,10-perylenetetracarboxylic dianhydride). The intermolecular interactions between nearest neighbors are quantum chemically analyzed on the basis of semi-empirical (ZINDO/S) Hartree-Fock calculations and a singly excited configuration interaction scheme. Supermolecular dimer states are projected onto a basis set of localized excitations. The nature of the lowest states is then completely explained as a superposition of molecular and low lying charge-transfer excitations. The CT excitations show a significant intrinsic transition dipole, which is oriented approximately parallel to the molecular planes and has a large component along the molecular M-axis. The exciton states in the one-dimensional stacks are described by a model Hamiltonian that includes interactions between three vibronic levels of the lowest molecular excitation and nearest-neighbor CT excitations. The three-dimensional crystal structure is considered by Frenkel exciton transfer between arbitrary molecules. This model is compared to polarized absorption spectra. With a small set of parameters, we can describe the key features of the absorption spectra, the polarization behavior, and the Davydov splitting. The variation of the polarization ratio for the various exciton states is analyzed as a direct qualitative proof for the mixing between Frenkel and charge-transfer excitons.
Author: Kikuo Cho
Publisher: World Scientific
ISBN: 9814491306
Category : Technology & Engineering
Languages : en
Pages : 496
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Book Description
At Yamada Conference LIII, papers on many novel materials and on novel phenomena in condensed matter physics were presented — for instance, the achievement of simultaneous creation of excitons and free-electron-hole pairs in rare gas solids, and a low frequency fluctuation of the spectral shift of indirect excitons in GaAs coupled quantum wells. Single molecule spectroscopy is a powerful tool for studying molecules including biological systems; the study of delocalization of excitons in the photosynthetic light harvesting antenna system was also reported. The proceedings thus contain many excellent papers dealing with current research topics on the excitonic processes in bulk, quantum wells, quantum dots and other confined systems. This book will serve as an excellent source of recent references and reviews for a wide range of researchers in physics, chemistry, engineering and biological sciences.The proceedings have been selected for coverage in:• Index to Scientific & Technical Proceedings (ISTP CDROM version / ISI Proceedings)
Author: Kikuo Ch?
Publisher: World Scientific
ISBN: 9810245882
Category : Science
Languages : en
Pages : 496
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Book Description
At Yamada Conference LIII, papers on many novel materials and on novel phenomena in condensed matter physics were presented ? for instance, the achievement of simultaneous creation of excitons and free-electron-hole pairs in rare gas solids, and a low frequency fluctuation of the spectral shift of indirect excitons in GaAs coupled quantum wells. Single molecule spectroscopy is a powerful tool for studying molecules including biological systems; the study of delocalization of excitons in the photosynthetic light harvesting antenna system was also reported. The proceedings thus contain many excellent papers dealing with current research topics on the excitonic processes in bulk, quantum wells, quantum dots and other confined systems. This book will serve as an excellent source of recent references and reviews for a wide range of researchers in physics, chemistry, engineering and biological sciences.The proceedings have been selected for coverage in: ? Index to Scientific & Technical Proceedings (ISTP CDROM version / ISI Proceedings)
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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This work offers a concept to predict and comprehend the electronic excited states in regular aggregates formed of quasi-one-dimensional organic materials. The tight face-to-face stacking of the molecules justifies the idealization of the crystals and clusters as weakly interacting stacks with leading effects taking place within the columnar sub-structures. Thus, the concept of the small radius exciton theory in linear molecular chains was adopted to examine the excitonic states. The excited states are composed of molecular excitations and nearest neighbor charge transfer (CT) excitations. We analyzed the structure and properties of the excited states which result from the coupling of Frenkel and CT excitons of arbitrary strength in finite chains with idealized free ends. With the help of a partially analytical approach to determine the excitonic states of mixed Frenkel CT character by introducing a complex wave vector, two main types of states can be distinguished. The majority of states are bulk states with purely imaginary wavevector. The dispersion relation of these state matches exactly the dispersion relation known from the infinite chain. The internal structure of the excitons in infinite chains is directly transferred to the bulk states in finite chains. TAMM-like surface states belong to the second class of states. Owing to the damping mediated by a a non-vanishing real part of the wavevector, the wave function of the surface states is localized at the outermost molecules. The corresponding decay length is exclusively determined by the parameterization of the coupling and is independent of the system size. It can therefore be assigned as a characteristic quantum length which plays a vital role for the understanding of system-dependent behavior of the states. The number and type of surface states occurring is predicted for any arbitrary coupling situation. The different nature of bulk and surface states leads to distinct quantum confinement effects. Two regi.
Author: G¿nter Gauglitz
Publisher: John Wiley & Sons
ISBN: 3527654720
Category : Science
Languages : en
Pages : 2011
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Book Description
This second, thoroughly revised, updated and enlarged edition provides a straightforward introduction to spectroscopy, showing what it can do and how it does it, together with a clear, integrated and objective account of the wealth of information that may be derived from spectra. It also features new chapters on spectroscopy in nano-dimensions, nano-optics, and polymer analysis. Clearly structured into sixteen sections, it covers everything from spectroscopy in nanodimensions to medicinal applications, spanning a wide range of the electromagnetic spectrum and the physical processes involved, from nuclear phenomena to molecular rotation processes. In addition, data tables provide a comparison of different methods in a standardized form, allowing readers to save valuable time in the decision process by avoiding wrong turns, and also help in selecting the instrumentation and performing the experiments. These four volumes are a must-have companion for daily use in every lab.
Author: Thorsten U. Kampen
Publisher: John Wiley & Sons
ISBN: 3527643745
Category : Science
Languages : en
Pages : 258
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Book Description
This up-to-date reference for students and researchers in the field is the first systematic treatment on the property measurements of organic semiconductor materials. Following an introduction, the book goes on to treat the structural analysis of thin films and spectroscopy of electronic states. Subsequent sections deal with optical spectroscopy and charge transport. An invaluable source for understanding, handling and applying this key type of material for physicists, materials scientists, graduate students, and analytical laboratories.
Author:
Publisher: Elsevier
ISBN: 0080519210
Category : Technology & Engineering
Languages : en
Pages : 509
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Book Description
The first book devoted to a systematic consideration of electronic excitations and electronic energy transfer in organic crystalline multilayers and organics based nanostructures(quantum wells, quantum wires, quantum dots, microcavities). The ingenious combination of organic with inorganic materials in one and the same hybrid structure is shown to give qualitatively new opto-electronic phenomena, potentially important for applications in nonlinear optics, light emitting devices, photovoltaic cells, lasers and so on. The book will be useful not only for physicists but also for chemists and biologists.To help the nonspecialist reader, three Chapters which contain a tutorial and updated introduction to the physics of electronic excitations in organic and inorganic solids have been included. * hybrid Frenkel-Wannier-Mott excitons * microcavities with crystalline and disordered organics * electronic excitation at donor-acceptor interfaces * cold photoconductivity at donor-acceptor interface * cummulative photovoltage * Feorster transfer energy in microcavity * New concepts for LEDs
Author: Karin Schmidt
Publisher:
ISBN:
Category :
Languages : en
Pages : 126
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Author: Nicolaas Bloembergen
Publisher: Compositori
ISBN:
Category : Science
Languages : en
Pages : 380
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