The interband absorption spectra of a system with Gaussian site diagonal disorder are calculated in the coherent potential approximation. electron-hole vertex part due to stochastic correlation is taken into account. relaxation k -selection rule and effect localization studied through calculation optical transition matrix elements. It clarified that band tail states contribute an exponential (the so-called Urbach tail) as result interplay between transfer energy Gaussian-distributed...

Excitation-energy transfer (EET) has been observed to be very rapid from B800 B850, between two circular aggregates of bacteriochlorophyll molecules (BChls), in the light-harvesting antenna complex LH2 photosynthetic purple bacteria. This EET cannot understood within framework Förster's formula, since luminescence spectrum overlaps little with absorption B850. The present work shows that it can rationalized on basis a recently proposed formula for molecular aggregates. differs one when...

Exciton states in conjugated polymers are theoretically studied the Su-Schrieffer-Heeger model supplemented by long-range Coulomb interactions. The relationship between exciton energies and basic interaction parameters is clarified, demonstrating special nature of one-dimensional excitons. binding lowest singlet triplet excitons depend sensitively upon on-site energy. Relevant experiments polydiacetylene can be explained present using moderate strength.

Excitons in conjugated polymers are studied theoretically the Su-Schrieffer-Heeger model supplemented by long-range Coulomb interactions. The relationship between exciton energies and basic interaction parameters is clarified. Linear third-order nonlinear optical susceptibilities (two-photon absorption, electroabsorption, third-harmonic generation) have been calculated, elucidating significance of singlet triplet excitons unbound electron-hole pairs. Using only moderate strength, various...

HESX1/Hesx1 is a member of the paired-like class homeobox genes and essential for pituitary forebrain development. Mice with targeted homozygous deletion Hesx1 show severe central nervous system defects, absence optic vesicles, very small anterior gland. This phenotype similar to abnormalities observed in human disorder called septo-optic dysplasia, syndromic form congenital hypopituitarism. To date, four missense mutations HESX1 have been described individuals phenotypes ranging from...

The modulus and phase of the complex third-order nonlinear optical (NLO) susceptibility \ensuremath{\chi}${\mathrm{\ifmmode \tilde{}\else \~{}\fi{}}}^{(3)}$(-3\ensuremath{\omega};\ensuremath{\omega},\ensuremath{\omega},\ensuremath{\omega}) have been measured on an all-trans silicon polymer, poly(dihexylsilane), over a wide photon energy range. Several distinct structures observed in \~{}\fi{}}}^{(3)}$ spectra are excellent agreement with theoretical results one-dimensional (1D) exciton...

Effects of Coulomb interactions and lattice fluctuations in the optical-absorption spectra ${\mathrm{C}}_{60}$ ${\mathrm{C}}_{70}$ are theoretically investigated by using a tight-binding model with long-range interaction bond disorder. Anisotropy effects also considered. Optical calculated Hartree-Fock approximation followed configuration method. The main conclusions as follows. (1) broad peaks at excitation energies, 3.7, 4.7, 5.7 eV, observed experiments molecules solution, reasonably...

The effect of long-range Coulomb interaction between an electron and a hole on the optical absorption spectrum one-dimensional Peierls insulator is studied theoretically. Energy levels oscillator strengths exciton states in gap line shape continuous (interband transitions) above are calculated by taking interatomic nature transition matrix element into account. turns out to be great significance, sense that even very weak induces anomalously large strength lowest ( n =0) state.

Linear and nonlinear optical spectra (one-photon two-photon absorption, photoluminescence, electroabsorption spectra) have been investigated for solid thin films of polysilanes with a variety conformations, such as trans-planar, alternating trans-gauche (TGTG' type), 7/3 helical, disordered backbone structures. Optical revealed features one-dimensional exciton states characteristic the respective conformations. In particular, lowest allowed second parity-forbidden (or allowed) transitions...

Dynamics of an electron in quasiperiodic systems is studied numerically. Calculations are carried out for the one-dimensional tight-binding model with diagonal or off-diagonal modulation obeying Fibonacci sequence. The width wavepacket put on a single site at time t =0 exhibits such overall evolution as \(\sqrt{\langle\varDelta x^{2}\rangle}\sim t^{\alpha}\) (0<α<1). dynamical index α decreases continuously increasing strength. This anomalous power-law diffusion successfully interpreted...

ADVERTISEMENT RETURN TO ISSUEArticleNEXTGenerating function for electronic spectra of polyatomic moleculesShaul Mukamel, Shuji Abe, and Reza IslampourCite this: J. Phys. Chem. 1985, 89, 2, 201–204Publication Date (Print):January 1, 1985Publication History Published online1 May 2002Published inissue 1 January 1985https://pubs.acs.org/doi/10.1021/j100248a001https://doi.org/10.1021/j100248a001research-articleACS PublicationsRequest reuse permissionsArticle Views254Altmetric-Citations65LEARN...

A novel microscopic mechanism of bidirectional structural changes is proposed for the photoinduced magnetic phase transition in Co-Fe Prussian blue analogs on basis ab initio quantum chemical cluster calculations. It shown that local potential energies various spin states Co are sensitive to number nearest neighbor Fe vacancies. As a result, forward and backward most readily initiated by excitation different regions photons. This suggests an effective strategy realize reversible transitions...

The formation of polarons and bipolarons in conjugated polymers with nondegenerate ground states is studied theoretically. We use the Pariser-Parr-Pople model combined Su-Schrieffer-Heeger electron-lattice coupling a Brazovskii-Kirova-type symmetry-breaking interaction. relative stability systematically within unrestricted Hartree-Fock approximation as function parameters doping concentration. Coulomb interactions significantly suppress bipolarons, for realistic doped carriers are most...

The dynamics of an electron in a one-dimensional tight-binding model with incommensurate sinusoidal modulation (Harper's model) is studied numerically. width wavepacket put on single site at the time t =0 exhibits such asymptotic evolution as \(\sqrt{\langle\varDelta x^{2}\rangle}\sim t^{\alpha}\), where dynamical index α takes only three values α=1 for V < c , α=0 > and α=α (a value near 1/2) = strength critical value. This behavior striking contrast that Fibonacci chains, which can take...

We report electron spin resonance (ESR) studies on field-induced charge carriers in regioregular poly(3-hexylthiophene) (RR-P3HT) and poly(3-octylthiophene) (RR-P3OT) for metal–insulator–semiconductor (MIS) diode structures with Al 2 O 3 as an insulating layer. The ESR signals ( g ∼2.002) were clearly observed; their intensities monotonically increased the absolute value of gate bias accumulation mode a saturation behavior at higher voltages. consistent those photogenerated positive polarons...

Theoretical investigation with Monte Carlo simulations predicts that thermal spin-switching hysteresis of transition-metal complexes appears even in nanoparticles, but the width does not depend only on interaction strength between molecules also strongly shape and size particles.

The dynamics of an electron described by the one-dimensional tight-binding Hamiltonian with quasiperiodic (Fibonacci) modulation is studied numerically. width initially localized wave packet found to increase time t in overall power-law form \ensuremath{\sim}${t}^{\ensuremath{\alpha}}$ (0&lt;\ensuremath{\alpha}&lt;1). exponent \ensuremath{\alpha} continuously decreases increasing strength modulation. Moreover, prominent hierarchical oscillations are occur case strong These results explained...

The mechanism of the heat-induced charge transfer observed in Prussian-blue compounds ${\mathrm{K}}_{1\ensuremath{-}2x}{\mathrm{Co}}_{1+x}\mathrm{Fe}(\mathrm{CN}{)}_{6}$ is studied theoretically connection with photoinduced magnetism. In case $x=0,$ our first-principles band calculation confirms that band-gap excitation corresponds to from $\mathrm{Fe}\ensuremath{-}d\ensuremath{\varepsilon}$ $\mathrm{Co}\ensuremath{-}d\ensuremath{\gamma}$ orbitals. By increasing lattice constant...

A model of the deformable charge density wave (CDW) coupled to impurities in three dimensions is studied with computer experiments. Low energy states adiabatic potentials are for a finite system case moderately high concentration impurities. Special attention paid nature collective pinning and phase slippage processes accompanying translational motion CDW. It found that domain size single process has broad distribution, typically over two orders magnitude volume. This distribution may be...