bluuebunny/crossref_metadata_2025_split huggingface dataset:
Charge ordering in EDO‐TTF salts and their optical spectra: toward the first‐principles understanding of photoinduced phase transition
Authors: Iwano Kaoru , Shimoi Yukihiro 
Published: October 2008

AbstractA new scheme to calculate the ground and excited states of molecular crystals has been proposed for the purpose of studying their photoinduced phase transitions and demonstrated in a quasi‐one‐dimensional compound, (EDO‐TTF)2PF6, by the present authors [Phys. Rev. B 77, 075120 (2008)]. The principal results in that paper have been the successfully reproduced (0110)‐type charge ordering in the ground state and the optical conductivity spectrum consistent with the observed one.In this article, we explain technical and scientific details that have not been touched in the previous paper. In particular, we are concerned with the validity of our scheme; a cluster calculation augmented by self‐consistent environmental charges. The detailed behavior of the convergence of the self‐consistency is discussed. In addition, its effectiveness in other cases is also checked, with the high‐temperature phase as the first extension. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Charge transfer processes in cyano‐bridged transition metals
Authors: Kamioka Hayato , Moritomo Yutaka , Kosaka Wataru , Ohkoshi Shin‐ichi 
Published: October 2008

AbstractWe have applied a time‐resolved absorption spectroscopy to investigate the charge transfer (CT) processes in the Prussian Blue‐type cyanides MII[FeIII(CN)6]0.675H2O (M = Mn, Co) embedded in a Nafion film. In the Mn‐Fe cyanide, we observed the bleaching of the CT band at 2.4 eV, similar to that found in the Co‐Fe cyanide.We found that the lifetime of the photo‐induced CT state in Mn‐Fe cyanide shows significant dependence on the excitation photon energy. This is in sharp contrast to the case of the Co‐Fe cyanide. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of external magnetic field and confinement on spectrum rearrangement and exciton polaritons in optical microcavity
Authors: Kaputkina Natalia , Lozovik Yuri 
Published: October 2008

AbstractInfluence of external magnetic field and confinement on direct and spatially‐indirect excitons is studied. Exciton‐photon interaction and exciton polariton formation are discussed for single and coupled quantum wells or quantum dots embedded in optical microcavity. Possibility to control polariton resonance, polariton splitting and polariton dispersion by magnetic field is studied analitically and numerically. Magnetic field changes effective mass of magnetoexciton. Magneticfield increases effective steepness of confining potential in quantum dots also. This leads to the transformation of exciton energy spectrum. At low temperatures spontaneous coherence and Kosterlitz‐Thouless transition to superfluid state of exciton polaritons in the system of coupled quantum wells embedded in microcavity or Bose‐Einstein condensation of exciton polaritons in the system of coupled quantum dots embedded in optical microcavity can take place. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical studies of hydrogenbonded dielectrics TlH2PO4
Authors: Kawai Taketoshi , Ohno Nobuhito 
Published: October 2008

AbstractWe have for the first time investigated optical properties of thallium dihydrogen phosphate TlH2PO4 (TDP) up to vacuum ultraviolet energy region at low temperature. The remarkable dispersion‐like structures due to the first exciton transitions are observed around 5.8 eV above the fundamental absorption edge at 5.2 eV. The origin of the first excitons in TDP is ascribed to the cationic transition from 6s2 to 6s 6p electronic states in Tl+ ions.In the higher energy region, characteristic peak structures appear at 15.6 and 16.7 eV. The peak structures are attributed to the core excitons based on the transitions from 5d106s2 to 5d96s26p states in Tl+ions. A broad luminescence band with a large Stokes shift is observed at 2.9 eV, stimulated efficiently at the first exciton transition region. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoluminescence of forsterite single crystals excited by vacuum ultraviolet radiation
Authors: Kitaura Mamoru , Ohnishi Akimasa 
Published: October 2008

AbstractEmission and excitation spectra of forsterite have been measured using synchrotron radiation. The 2.55 eV and 2.85 eV bands dominates the emission spectra under excitation above and below the fundamental absorption edge at 7.6 eV, respectively. From the feature of excitation spectra, the 2.55 eV band is assigned to an intrinsic origin in forsterite. That is, this band most likely originates from a self‐trapped exciton (STE) state. The 2.85 eV band is ascribed to an extrinsic origin such as imperfections. The excitation spectrum for the 2.55 eV band exhibits the threshold for the electron‐hole (e ‐h) multiplication at around 21 eV, which is caused by inelastic scattering of hot photoelectrons with valence electrons. The structure of STEs and e ‐h relaxation processes induced by vacuum ultraviolet (VUV) photons are discussed on the basis of a comparison of experiment and theoretical calculation. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optically induced lattice distortion and its spatial diffusion in the relaxed excited state of a quantum paraelectric material
Authors: Kohmoto T. , Hatano N. , Yamaki M. , Koyama Y. , Moriyasu T. 
Published: October 2008

AbstractWe have investigated the diffusion dynamics of the optically induced lattice distortion in the quantum paraelectric region of strontium titanate SrTiO3. The time evolution of the lattice distortion, which is accompanied by the polarization in the relaxed excited state, was observed by using the polarization spectroscopy with the pump‐probe technique. The observed signal of the optically induced lattice distortion has a component which decays in the nanosecond region.The decay curve of the lattice distortion depends on the beam diameter. The relaxation time becomes shorter as the beam diameter is decreased. We observed the lattice distortion induced by the separated pump beam from the probe beam. The signal of the lattice distortion appears later as the separation between the pump and probe beams becomes larger. These experimental results suggest that the optically induced lattice distortion diffuses spatially. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cavity polariton dispersion of a single‐crystalline anthracene film embedded in a microcavity
Authors: Kondo H. , Tongu K. , Yamamoto Y. , Yamamoto S. , Kurisu H. 
Published: October 2008

AbstractWe study anisotropic behavior of cavity polaritons in an organic microcavity composed of a single crystalline anthracene film grown into the gap of the Fabry‐Perot cavity by a method through capillary action. The anisotropic response of the cavity polariton appeared on the spectra depending on the linear polarized directions; two kinds of the polarization correspond to the principal axes of anthracene crystal. Transmission spectra were measured with various thickness of the anthracene film. The peak‐shift of the lower polariton mode depending on the thickness was obviously observed, whereas that of the upper polariton mode was not clearly observed be cause of the complicated shape of the spectra. This behavior for the upper polariton mode was analyzed on the basis of the convolution between the spectra of the cavity mode and the absorption due to the vibronic transition in anthracene. Cavity‐polariton dispersion as a function of thickness was obtained from peak‐shift on the spectra. Each thickness was determined by spectral fitting through calculation using the transfer matrix theory. Large vacuum Rabi splitting energies of this system were obtained from the dispersion as 0.20 and 0.34 eV for two kinds of the polarizations. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Exciton and biexciton properties in GaN nanocolumn: dependence on morphology and diameter
Authors: Kouyama Kazuaki , Inoue Masaya , Inose Yuta , Suzuki Naoki , Kunugita Hideyuki , Ema Kazuhiro , Sekiguchi Hiroto , Kikuchi Akihiko , Kishino Katsumi 
Published: October 2008

AbstractWe have investigated how the morphology and diameter of GaN nanocolumn affect the optical properties of exciton and biexciton. We measured photoluminescence (PL) of excitons in GaN nanocolumns at low temperature and found that the PL spectra depend on the column diameter. Changing the distance between the sample and the collimating lens, it was established that this phenomenon is due to the z ‐polarized PL radiated from the side surface. This result proves that the nano‐scale morphology produces a change in the optical properties. In addition, to elucidate the mechanism causing the increase of the biexciton binding energy observed in a previous experiment, we calculated the exciton binding energies by the variational method and also estimated their sizes. From the calculated results we can expect that the only biexcitons experience spatial confinement effect even when the nanocolumn width is much larger than the exciton Bohr radius. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamics of nuclear wave packet in the excited state of KCl F centers
Authors: Koyama Takeshi , Nakajima Makoto , Suemoto Tohru 
Published: October 2008

AbstractDynamics of nuclear wave packet at the F center in KCl at 5 K is investigated by frequency up‐conversion spectroscopy. The oscillation frequency of the nuclear wave packet is 6.0 THz, which lies in the LO phonon branch near the Γ point of the Brillouin zone. The luminescence intensities decay slower in the low energy side of the stationary luminescence spectrum than in the high energy side. The transient luminescence spectra show relatively high intensities in the low energy side. These two features indicate the existence of the second 2s ‐2p level crossing near the relaxed excited state. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photo‐induced effect in quantum paraelectric materials: Transient birefringence measurement
Authors: Koyama Y. , Moriyasu T. , Okamura H. , Yamada Y. , Tanaka K. , Kohmoto T. 
Published: October 2008

AbstractThe photo‐induced effects in quantum paraelectric materials, strontium titanate SrTiO3 and Ca‐doped SrTiO3, are investigated. The observed birefringence for Cadoped SrTiO3 shows that an optical anisotropy along the [100] axis is generated by the ultraviolet (UV) illumination. The transient birefringence in a pulsed electric field is studied to probe the dynamical property of the polarization under dark and UV illumination.Under the UV illumination, the change of birefringence is reduced, and the dielectric response of relaxation type was observed both in SrTiO3 and in Ca‐doped SrTiO3. It was found that the ferroelectric phase transition temperature is shifted toward the lower temperature side under the UV illumination. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electron‐phonon effect on excitons in quasi‐2D ternary mixed crystal of polar semiconductors
Authors: Liang X. X. , Song Tie‐Lei 
Published: October 2008

AbstractThe electron‐phonon effect on quasi‐two‐dimensional (2D) Wannier excitons in ternary mixed crystal systems of polar semiconductors is studied. The binding energy of the 2D exciton is variationally calculated and the numerical results for several II‐VI and III‐V as well as III‐nitride compound semiconductors are given. The results show more remarkable electron‐phonon effect in 2D systems than that in three‐dimensional (3D) case. The obvious nonlinearity of the electron‐phonon interaction contributions to exciton binding energies is also theoretically found, in special for the systems composed of nitride‐base compounds. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Engineering molecular aggregate spectra
Authors: Malyshev V. A. , Malyshev A. V. 
Published: October 2008

AbstractWe show that optical properties of linear molecular aggregates undergo drastic changes when aggregates are deposited on a metal surface. The dipole‐dipole interactions of monomers with their images can result in strong re‐structuring of both the exciton band and the absorption spectrum, depending on the arrangement of the monomer transition dipoles with respect to the surface. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of disorder on the relaxation of photoexcited states in one‐dimensional Mott insulators
Authors: Segawa Mami , Takahashi Akira , Aihara Masaki 
Published: October 2008

AbstractWe theoretically investigate the effect of static disorder on the dynamics of photoexcited states in onedimensional Mott insulators. We adopt the Pariser‐Parr‐Pople model, where disorder is introduced in the site energy and the transfer integral. We numerically calculate the time development of the state excited by a light pulse, and investigate the time dependence of the nearest‐neighbor spin‐spin interaction energy, the on‐site Coulomb interaction energy, and the kinetic energy of photogenerated charges. In the weaker excitation case, the energy transfer from the charge degrees of freedom to the spin degrees of freedom does not occur in the regular systems as a result of the spin‐charge separation. When the disorder in the transfer integral is introduced, the spin‐spin interaction energy changes with time after photoexcitation, showing that the spin‐charge coupling is induced in this case.The effects of the disorder in the site energy on the spincharge coupling are much weaker than those in the transfer integral. On the contrary, the energy transfer from the on‐site Coulomb interaction energy to the kinetic energy is strongly suppressed by these two kinds of disorders. In the stronger excitation case, the spin and the charge degrees of freedom are coupled in the photoexcited states, and the two kinds of energy transfers occur even in regular systems. Furthermore, these energy transfers occur in irreversible way, suggesting that these transfers are relaxation phenomena. These relaxations are enhanced by the disorders. There are no significant differences in the effects of disorders on these relaxations between the disorder in the site energy and that in the transfer integral. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Polaron effect on the binding energies of excitons in quantum wells under hydrostatic pressure
Authors: Zhao G. J. , Liang X. X. , Ban S. L. 
Published: October 2008

AbstractUnder hydrostatic pressure, the polaron effect on the binding energies of excitons in quantum wells is discussed by a variational method by considering the influence of finite barriers and the coupling of an exciton with bulk confined longitudinal optical, half space longitudinal optical and interfacial optical modes. A quasi‐ two dimensional Lee‐Low‐Pines like unitary transformation is adopted to deal with the exciton‐phonon interaction and the pressure dependence of physical parameters is also taken into account in the calculation. As an example, the numerical computation is applied to the GaAs/Alx Ga1–x As quantum wells. The result shows that the exciton binding energies increase with presure from 0 to 40 kbar. The maximum energy shift is about 21% for the given quantum well width and Al concentration x = 0.15. The exciton‐phonon interaction energies also increase with pressure and the effects of three kinds of different exciton‐phonon interactions are discussed in detail for different widths of quantum wells. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Revisiting the foundations of the quantum theory of atoms in molecules: Toward a rigorous definition of topological atoms
Authors: Nasertayoob Payam , Shahbazian Shant 
Published: October 2008

AbstractAn explicit classification of consistent variational constraints within the context of the “quantum theory of proper open subsystems” as well as the “quantum theory of atoms in molecules” (QTAIM) it presented. It is demonstrated that the general variational procedure is not sensitive enough to discriminate between different mathematically consistent variational conditions. The uniqueness of the regional kinetic energy is employed to derive the net zero‐flux condition and the regions satisfying this condition are named asquantum divided basins. A modified form of the local zero‐flux is proposed in order to define topological atoms within the context of the orthodox QTAIM. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Calculation of ionization potential and chemical hardness: A comparative study of different methods
Authors: Shankar R. , Senthilkumar K. , Kolandaivel P. 
Published: October 2008

AbstractThe suitability of ab initio and density functional theory (DFT) methods for an accurate determination of ionization potential and chemical hardness is the subject of systematic analysis for a panel of molecules. Comparison of experimental ionization potential values with theoretical results indicates that using orbital energies obtained from the so‐called statistical average of orbital potential (SAOP) model exchange correlation potential in Koopman's theorem is an efficient method to evaluate the correct ionization potentials. Experimental ionization potential and electron affinity values have been used to calculate the absolute chemical hardness. Comparative results show that the chemical hardness values calculated by using Hartree–Fock orbital energies in Koopman's theorem are sufficiently good rather than Möller–Plesset second order perturbation method and DFT‐generalized gradient approximation (GGA) exchange correlation functional orbital energies. A new method given by Tozer et al. (J Phys Chem A 2005, 109, 8923) to calculate the chemical hardness works well with the orbital energies of DFT‐GGA functionals together with the ionization potential values calculated from SAOP orbital energies. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Theoretical study on interactions between thiourea S‐monoxide and water
Authors: Peng Ke , Yang Wen , Zhou Weiqun 
Published: October 2008

AbstractThis work investigated the hydrolyzation of thiourea monoxide using density functional theory (DFT) and Møller–Plesset second‐order (MP2) Theory. We obtained the equilibrium structures and other molecular properties of the clusters. The results show that thiourea monoxide has a good solubility in water solvent, and as indicated, the binding energies of the clusters are increased progressively by the addition of water molecules. Furthermore, the increases of the distance(CS) and (SO) by the addition of water molecules indicate that the strength of the CS and SO bonds are weakened. When n = 7 (n, the number of water molecules), the CS bonds of Clusters VII ruptured. We conclude that thiourea monoxide can be decomposed in aqueous solution. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
A guiding simulation research on developing promising energetic materials
Authors: Liu Min‐Hsien , Cheng Ken‐Fa , Chen Cheng , Hong Yaw‐Sun 
Published: October 2008

AbstractThis investigation is motivated by the representative synthesis reaction of 1,4,5,8‐tetranitro‐1,4,5,8‐tetraazadecalin (TNAD): ethylene diamine is replaced by 1,1,diamino‐2,2‐dinitroethene (FOX‐7) or 1,3,5‐triamino‐2,4,6‐trinitrobenzene (TATB) to react with glyoxal in order to subsequently obtain promising high energy density materials. The hybrid density functional theory method is used in calculations for some series of compounds with NNO2 and CNO2 functional groups. First, we create the corresponding Cartesian coordinates of the molecules under investigation and obtain their optimized molecular geometry; the molecular enthalpy can then be used to calculate the molecular detonation heat upon explosion. Furthermore, the target molecular volumes are obtained using the group additivity approach, which are then transferred into molecular densities. The densities and detonation heats of the corresponding energetics are carried into the Kamlet–Jacobs empirical equations to determine the related detonation velocities and detonation pressures. It was found that 10 of 14 TATB‐ and FOX7‐related molecular derivatives have detonation velocities between 9,302 and 1,1122 m/s and between 396 and 646 kbar, and are superior in performance to the traditional octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX) explosive. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Stability analysis of the neutral noble gas molecules FNgX and their anions FNgX− (Ng = He, Ar, Kr; X = O, S)
Authors: Li Yun , Ai Hongqi , Qi Zhongnan , He Wei , Zhang Liang 
Published: October 2008

AbstractThe structural stability and bonding energies of the neutral noble gas molecules FNgX and their anions FNgX− (Ng = He, Ar, Kr; X = O, S) are discussed at the CCSD(T)/aug‐cc‐pVnZ (n = D, T) levels. Results reveal that only two neutral FKrX molecules are stable, whereas their FHeX and FArX counterparts are not. All their anions are stable and the stability mainly derives from the contribution of the extra electron, i.e., the attachment of the electron greatly enhances the orbital interactions of two bonds, FNg and NgX. Different from the anion counterparts, the electrostatic interaction energy plays a crucial role in the FKrX stability. Compared with those unstable FHeX and FArX counterparts, the enough charge distribution over each atom of FKrX ensures the effective bonding between F and Kr, and between Kr and X, consequently strengthen the stability of the neutral FKrX (X = O, S) structures. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
A design tool for planning emulsified oil‐injection systems
Authors: Weispfenning Aaron M. , Borden Robert C. 
Published: October 2008

AbstractEmulsified oils have been used to stimulate anaerobic bioremediation at hundreds of sites contaminated with chlorinated solvents, perchlorate, heavy metals, and nitrate. A simple spreadsheet‐based tool has been developed to assist in the design of injection‐only systems for distributing emulsified oils in barriers and area treatments. This tool allows users to quickly compare the relative costs and performance of different injection alternatives and identify a design that is best suited to site‐specific conditions. Contact efficiency is estimated using results of prior numerical model simulations and dimensionless scaling factors that relate the volume of oil and water injected to treatment‐zone dimensions. Sensitivity analysis results indicate that maximum oil retention is one of the most important factors controlling system performance and cost. © 2008 Wiley Periodicals, Inc.