Comparing long-range corrected functionals in the cis–trans isomerisation of the retinal chromophore

Earlier results for the 11-cis to all-trans isomerisation of the retinal chromophore after photoexcitation, studied using time-dependent density functional theory with the hybrid CAM-B3LYP functional, are compared with new results using other long-range corrected DFT functionals. The TDDFT S₀ and S₁ minimum energy paths have been compared with the approximate coupled-cluster method RI-CC2. All calculations were consistent in producing an additional avoided crossing minimum on the S ₁ minimum energy path lying approximately halfway between the 11-cis and all-trans S₁ minima. In this minimum on the S₁ potential energy surface, the retinal chromophore has inverted bond order in its carbon chain and lower energy than it has in both the 11-cis and all-trans S₁ minima.     

Quark model study of the η photo-production:

An extensive and systematic study of the recent η photo-production data up to 1.2 GeV is presented within a chiral constituent quark model. A model embodying all known nucleonic resonances shows clear need for a yet undiscovered third S₁₁ resonance in the second resonance region, for which we determine the mass (1.729 GeV) and the total width (183 MeV). Furthermore, we extract the configuration mixing angles, an important property of the quark-quark interaction in the quark model, for the resonances S ₁₁(1535) and S ₁₁(1650), as well as for the resonances D ₁₃(1520) and D ₁₃(1700). Our results agree well with the quark model predictions. In addition, the partial ηN decay widths and/or the photo-excitation helicity amplitudes for the nucleonic resonances S ₁₁(1535), S ₁₁(1650), P ₁₁(1710), P ₁₃(1720), D ₁₃(1520), D ₁₃(1700), D ₁₅(1675), and F ₁₅(1680) are also obtained in this approach. Received: 14 February 2001 / Accepted: 22 June 2001     

Gravity on Finite Groups

Gravity theories are constructed on finite groups G. A self-consistent review of the differential calculi on finite G is given, with some new developments. The example of a bicovariant differential calculus on the nonabelian finite group S ₃ is treated in detail, and used to build a gravity-like field theory on S ₃. Received: 11 November 1999 / Accepted: 11 December 2000     

Molecular magnetism in closo-azadodecaborane supericosahedrons

ABSTRACT

The connection of 12 s = ½ closo-azadodecaborane radical units (NB₁₁H₁₁?), where a hydrogen atom is removed from the nitrogen atom, produces a supericosahedron [(NB₁₁H₆?)₁₂]^(S), S being the total spin of the system. This work describes the study of the low-lying energy spin-projected states of this supericosahedron with two different geometrical arrangements, each nitrogen atom pointing (1) inwards or (2) outwards with respect to radial axes. These spin-projected states are mapped into a Heisenberg spin Hamiltonian, thus allowing the determination of coupling constants between magnetic sites. The eigenvalues of this model Hamiltonian then predict the ground spin state and the corresponding combinations of spin orientations of the magnetic centres. We show that the energy minimum in the [(N_in/outB₁₁H₆?)₁₂]^(S) systems corresponds to a high-spin S = 6 state.     

Letter: Quantum Kaluza-Klein Cosmologies

In the No-boundary Universe with d = 11 supergravity, under the S _n × S _11–n Kaluza-Klein ansatz, the only seed instanton for the universe creation is a S ₇ × S ₄ space. It is proven that for the Freund-Rubin, Englert and Awada-Duff-Pope models the macroscopic universe in which we are living must be 4- instead of 7-dimensional without appealing to the anthropic principle.     

Model-independent Breit-Wigner parameters of S 11(1535) and S 11 (1650) nucleon resonances from experimental data on η meson photoproduction on protons

The results of phenomenological partial-wave analysis of angular distributions for the process γp → νp measured at the Tohoku University (Japan) and model-independent estimates of Breit-Wigner parameters of S ₁₁(1535) and S ₁₁(1650) nucleon resonances obtained based on these data are presented. Original Russian Text ? E.V. Balandina, E.M. Leikin, N.P. Yudin, 2009, published in Vestnik Moskovskogo Universiteta. Fizika, 2009, No. 1, pp. 87–89.     

Optical behavior of composite carbonaceous aerosols: DDA and EMT approaches

Atmospheric particles may contain a small amount of black carbon (BC) that may affect their optical properties. These optical properties also depend strongly on the particle morphology and internal topology. The efficiency factors for scattering Q_sca, absorption Q_abs, extinction Q_ext, backscattering Q_bk, as well as the asymmetry parameter cos, linear polarization P, and scattering phase functions S₁₁ are analyzed in detail as functions of morphology and internal topology. Backscattering quantities (like Q_bk and P and S₁₁ at large scattering angles) are affected most significantly. The behavior of these quantities depends strongly on the internal mixing of the constituent materials making up the particle. Effective medium theories (EMTs), which assume that the particle is homogeneous and are applied frequently in radiative transfer studies, can underestimate Q_sca and S₁₁ especially when high carbon contents are considered. Contrarily, EMTs also tend to overestimate the values of the asymmetry parameter and Q_abs.     

飞秒时间分辨拉曼光谱用于研究β-胡萝卜素单重激发态内转换和振动弛豫过程

搭建了飞秒时间分辨受激拉曼光谱(FSRS)装置,并用于研究全反式β-胡萝卜素单重电子激发态超快内转换和振动弛豫过程.基于三脉冲“抽运-探测”方案搭建的时间分辨受激拉曼光谱装置同时实现了150fs的时间分辨率和23.7cm^-1的光谱分辨率,光谱检测范围为300—4000cm^-1.对全反式β-胡萝卜素电子激发态的飞秒时间分辨拉曼光谱研究表明,β-胡萝卜素被激发到S₂态后,经由寿命约为0.3ps的中间态S_X态实 关键词： 飞秒时间分辨拉曼光谱 β-胡萝卜素 激发态内转换 振动弛豫     

The Spectrum of D = 11 Supergravity via Harmonic Expansions on S4 X S7

We derive the complete particle spectrum of the d = 11 supergravity compactified on AdS X S⁷, by analytically continuing AdS to S⁴, and using the Salam-Strathdee method of harmonic expansion on S⁴ X S⁷. The spectrum is arranged into supermultiplets labelled by an integer l = 0, 1, 2,. The massless supermultiplet corresponds to l = 0. For the l'th supermultiplet we find a relation, involving the eigenvalues of the second order Casimir operators of SO(3, 2) and SO(8), given by 2C₂[SO(3, 2)] + C₂[SO(8)] = 3/2(l + 2) (l + 4).     

Photoproduction of $\eta$-mesons on protons in the resonance region: The background problem and the third S11-resonance

We have constructed an isobar model for the -photoproduction on the proton in the energy region up to the photon lab energy K ₀ = 3 GeV. The database involved into the fitting procedure includes precise results for the cross-section and for the T-asymmetry of the process near threshold obtained at MAMI and ELSA as well as recent results for the -asymmetry and for the angular distribution measured at higher energies in Grenoble and also more recent measurements performed at JLab for the photon energies up to 2 GeV. The model includes twelve nucleon resonances: S ₁₁(1535), S ₁₁(1650), S ₁₁(1825), P ₁₁(1440), P ₁₃(1720), D ₁₃(1520), D ₁₅(1675), F ₁₅(1680), F ₁₇(1990), G ₁₇(2190), G ₁₉(2250), H ₁₉(2220), and the background consisting of the nucleon pole term and the vector meson exchange in the t-channel. To explain the observed energy dependence of the integrated cross-section, two s-wave resonances, S ₁₁(1650) and S ₁₁(1825), have to be taken into account along with the dominating S ₁₁(1535). The integrated cross-section as well as the angular distribution and -asymmetry predicted by the model are in good agreement with the data. Above the photon energy K ₀ = 2 GeV, the calculated cross-section exhibits an appreciable dependence on the - and -meson contribution, whose coupling with nucleons is not well defined. Several versions of extending the model to higher energies are considered.Received: 20 January 2004, Revised: 13 April 2004, Published online: 12 October 2004PACS: 13.60.Le Meson production - 25.20.Lj Photoproduction reactions     

Phase-reconstruction in photonic crystals from S-parameter magnitude in microstrip technology

A method based on Hilbert-transforms is used to reconstruct phase, group-delay and impulse response from magnitude-only information regarding the S ₁₁ and S ₂₁ parameters of photonic crystals (PC) constructed by periodically etching the ground plane of a microstrip line. Measurements show that for many practical cases this allows us to fully characterize the devices with a simple scalar network analyser instead of more sophisticated and expensive instrumentation, such as a vector network analyzer (VNA).     

Chiral constituent quark model study of the process γp → ηp <Superscript>⋆</Superscript>

A constituent quark model is developed for the reaction γp → ηp , allowing us to investigate all available data for differential cross-sections as well as single polarization asymmetries (beam and target) by including all of the PDG, one to four star, nucleon resonances (S₁₁, P₁₁, P₁₃, D₁₃, D₁₅, F₁₅, F₁₇, G₁₇, G₁₉, H₁₉, I_1,11, and K_1,13). Issues related to the missing resonances are also briefly discussed by examining possible contributions from several new resonances (S₁₁, P₁₁, P₁₃, D₁₃, D₁₅, and H_1,11).     

Isochoric temperature coefficient of surface tension andS o-parameter of quasi-spherical molecular liquids

The Sharma parameterS _o which is characteristic of molten alkali halides and polymers has also been shown to be characteristic of a wide variety of liquids. Calculated data using the volume expansivity of the liquid establish the constancy of theS _o-parameter which retains, on an average, a constant value of 1·11 for quasi-spherical molecular liquids. It is shown thatS _o-parameter is also related to volume expansivity of the surface layer of the liquid, temperature coefficient of surface tension of liquids and describes the temperature and volume or pressure dependence of thermodynamic Grüneisen parameter and isochoric heat capacity with significant contribution for influencing the thermoacoustic and surface tension properties of liquids.     

A Theoretical Description of the Photodissociation Spectrum of the H2O...HCl Complex

The effect of association of the water molecule and hydrogen chloride on the UV absorption bands is studied. Complete ab initio calculations for the H₂O...HCl complex in the S ₁ and S ₂ states are performed. A mathematical model using Airy functions is developed to describe the absorption cross-sections in a continuous spectrum. The form of the potential is determined by accurate ab initio calculations. The cross-sections of potential surfaces of lower electron states are found from ab initio calculations using the Hartree–Fock, configurational interaction, and multi-configurational interaction techniques. A complete vibrational analysis and an analysis of the change in the electron density for the S ₀ S ₁ transition on moving along the reaction coordinate allow a conclusion to be made on the feasibility of applying the model proposed to the H₂O...HCl complex. The results obtained in the framework of the model using Airy functions show reasonably good agreement with the experiment. For the H₂O...HCl heterodimer, the absorption band has the same structureless form as for the water monomer. The absorption band (peaking at 161 nm) is seen to shift towards short wavelengths as compared with the water monomer H₂O ( 167 nm).     

Propagation of spectral Stokes singularities of stochastic electromagnetic beams through atmospheric turbulence

The propagation of spectral Stokes singularities (vortices) of stochastic electromagnetic vortex beams through atmospheric turbulence is studied, where the electromagnetic Gaussian Schell-model (GSM) vortex beam is taken as an illustrative example. It is shown that the spectral Stokes vortices S ₁₂ (C-points), S ₂₃ and S ₃₁ introduced to describe the polarization singularities of stochastic electromagnetic beams appear in turbulence. The motion, creation, annihilation and polarization changes of S ₁₂, S ₂₃ and S ₃₁ vortices, as well as the handedness inversion of S ₁₂ vortices may appear as the propagation distance or one beam parameter varies. In the process the topological relationship holds true. In comparison with the free-space propagation, the variation of the refractive index structure constant C_n²C_{n}^{2} in atmospheric turbulence results in similar effects as above. The dependence of S ₁₂, S ₂₃ and S ₃₁ vortices on the propagation distance and beam and turbulence parameters are illustrated by numerical examples.     

Complex Harmonic-Oscillator Basis for the Relativistic Three-Body Problem

A complex harmonic-oscillator basis is employed for the three-body problem obeying S ₃-symmetry. Unlike a real basis it generates an additional quantum number (N _a ), in addition to the standard principal quantum number (N), and thus facilitates a more quantitative S ₃-classification of the various states than is usually possible. It is shown that certain bilinear forms with definite S ₃-symmetry properties, which can be constructed out of the linear harmonic-oscillator operators (a, a ^†) satisfy several uncoupled sets of SO(2, 1) algebras with spectra bounded from below. It is also briefly indicated how this S ₃-formalism can be adapted to the core structure of a more general relativistic three-particle system with unequal-mass kinematics through an appropriate choice of internal variables. Received May 11, 1994; revised November 3, 1994; accepted for publication November 23, 1994     

Crystal structure of polymorphous modifications of Tm2S3 and related compounds

The role of symmetry in crystal structure formation is revealed for the polymorphous modifications of Tm₂S₃ and related compounds Tm₁₅S₂₂, Tm₅S₇, and Tm₈S₁₁ using the procedure of selecting and analyzing close-packed planes with cationic, anionic, and combined motifs. The laws of mutual agreement between the cation and anion matrices determining the size of the unit cells are examined, and relationships between the specific cation volumes and symmetry are traced. Translated fromZhurnal Struktumoi Khimii, Vol. 39, No. 4, pp. 669–675, July–August, 1998.     

Properties of 80-MeV oxygen ion irradiated ZnS:Mn nanoparticles and exploitation in nanophotonics

ZnS:Mn nanoparticles of size variation 11–17 nm were synthesized by a simple and inexpensive chemical method and confirmed by transmission electron microscopy (TEM). Presuming electronic energy loss (S _e>S _n, S _n being nuclear energy loss) to be the dominant phenomenon, they were irradiated by 80-MeV energetic oxygen ions with fluence of 10¹¹ to 10¹³ ions/cm². Photoluminescence (PL) spectra revealed three major emission bands ~445 nm, ~582 nm and ~706 nm; which are ascribed to D–A pair transition, Mn emission and surface state led fluorescence activation. The recovery of Mn emission and tunable surface state emission have been observed with ion fluence variation. Infra-red (IR) spectra of irradiated samples show great extent of oscillation with respect to amplitude due to ion fluence variation however, phonon energy (~98 MeV) remains unchanged. The possible applications of these modified properties in nanophotonics are also highlighted.