Proceedings Volume 6165

Saratov Fall Meeting 2005: Laser Physics and Photonics, Spectroscopy and Molecular Modeling VI

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Proceedings Volume 6165

Saratov Fall Meeting 2005: Laser Physics and Photonics, Spectroscopy and Molecular Modeling VI

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Volume Details

Date Published: 12 July 2006
Contents: 6 Sessions, 32 Papers, 0 Presentations
Conference: Saratov Fall Meeting 2005 2005
Volume Number: 6165

Table of Contents

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Table of Contents

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  • Plenary Lecture
  • Laser Physics, Nonlinear Optics, and Electromagnetic Wave Propagation
  • Atoms in Laser Fields
  • Laser Interferometry and Quantum Optics
  • Spectroscopy and Molecular Modeling
  • English as a Communicative Tool in the Scientific Community
Plenary Lecture
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A semiclassical description of protonium formation in antiproton collisions with molecular hydrogen
W. A. Beck, L. Wilets, M. A. Alberg
In a departure from our previous work modeling antiproton capture on Helium, with it's relatively straightforward, fixed center target, extending the semiclassical approach to molecular hydrogen, i.e. a multi-center target with target masses identical to the projectile, requires that we revisit the fundamental nature of our model, including the momentum-dependent Heisenberg core used to stabilize electrons in the ground state. Happily, with minor modifications of the model parameters, it seems up to this new task. Here we discuss the main features of this revised model of a semiclassical molecular target, and use it to examine antiproton collisions with H2; details of the collision process are presented, including the energy and angular momentum states of incident antiprotons which result in formation of pp-, and the resulting distribution of protonium atomic states.
Laser Physics, Nonlinear Optics, and Electromagnetic Wave Propagation
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On compression of femtosecond pulses with basic and doubled frequencies
Vyacheslav A. Trofimov, Vladislav V. Trofimov
The possibility of high-intensity second harmonic formation with beam profile and pulse shape, which are similar to the Gaussian ones, under the cascading SHG with taking into account cubic nonlinear response of the medium is shown. The laser pulse with the doubled frequency has the intensity that is comparable with or greater than the intensity of the fundamental harmonic. The duration of the second harmonic pulse can be much smaller than the first harmonic pulse duration. We take into account the dispersion and diffraction of laser pulses and group velocity mismatching.
Laser cooling in extended solids taking into account the collective processes
The kinetics of the extended model of crystal doped by rare-earth ions in regime of anti-Stokes laser cooling has been considered taking into account the collective radiation effects. The system of master equations for impurities and pseudo-local phonons has been obtained. As would be expected, the collective radiation effects causes an acceleration in relaxation depletion of the phohon mode and therefore an increase of crystal cooling efficiency.
The pecularities of coherent population trapping resonances on fine structure levels for different light polarization
Tamara Karagodova, Alexander Karagodov
At the conditions of two-photon resonance the effect of coherent population trapping (CPT) can take place. The CPT may be observed as in absorption so in resonance fluorescence. The CPT is widely applied in high resolution spectroscopy, laser cooling, atomic optics and so on. Earlier the peculiarities of CPT resonances on fine structure levels of an atom have been considered on example of thallium atoms. It was shown that the form and number of resonances are influenced by geometry of experiment and initial conditions (initial level populations). As the investigations of CPT on fine structure levels are the object of interest last years, we have considered the numerical analysis of dependence the form of CPT resonances on fine structure levels of T1 atoms as lower levels of Λ-system on polarization of radiation fields. The cases of elliptical, linear and circular polarization have been considered.
Optimization of the fast frequency sweep parameters in high frequency electromagnetic field simulation by vector finite element method
A. D. Grigoriev, R. V. Salimov, R. I. Tichonov
Implementation of well-conditioned Fast Frequency Sweep in vector finite element electromagnetic field simulation is described. Some aspects of its application to problems with lossy medium, absorbing boundary conditions and lumped elements are discussed. Results of field simulation in several test microwave systems demonstrate high efficiency of the method. Expressions for matrix elements in frequency expansions are presented. Eigenvalues calculated in a wide frequency range of more then 2 octaves with maximum moment power 19 show good agreements with the analytical values. Dependence of frequency range width on maximum moment power is investigated. It is shown that widest frequency band for given maximum moments order and a central frequency is obtained with central frequency is set as mean geometrical value of minimum and maximum frequencies of the band.
Interaction of narrow-band signal components and complex behavior of PDE characteristics in x, t-plane
Yuriy N. Zayko
The paper is devoted to the discussion of the complex behavior of the characteristics of the partial differential equations (PDE), in particular, the equations of nonlinear geometrical optics, in the coordinate-time plane. It is shown that the interaction of narrow-band components of a signal leads to the absence of the intersection of these characteristics. Instead the characteristics demonstrate complex (oscillating) behavior that leads to many physical consequences. Some of them, namely, the oscillation the chirped pulse duration and the gap between the regions of the "past" and "future" determined with the help of photon signals, are discussed.
Laser effect in nonlinear 1D photonic crystal
We present the results of calculations of the spectral characteristics of finite length 1D PC with air-glass-doped layers. For these calculations we used the transfer matrix formalism. We present also the results of calculation accounting nonlinear deformation of the field distribution along the structure due to gain and refraction index saturation. The results of calculations of laser power are presented on the dependence from gain.
Dispersive wave generation in microstructured fiber with periodically modulated diameter
Andrey Konyukhov, Leonid Melnikov, Yuliya Mazhirina
The application of microstructured fiber with periodically modulated diameter for a flat supercontinuum generation is proposed. We report the results of numerical study of spectral broadening of low-order femtosecond solitons. It is shown that periodical modulation of phase-matching conditions leads to spectrum broadening and disappearing of spectral gap between spectra of soliton and dispersive wave. The shape of output spectrum depends on period of the modulation of diameter of microstructured fiber.
Atoms in Laser Fields
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Electron-positron pair creation by a multimode field of an optical laser
N. A. Tarakanov, A. V. Prozorkevich, S. A. Smolyansky, et al.
The investigation of the electric field of modern powerful optical lasers predicts the creation of a dense quasiparticle plasma in the foci of counter-propagating optical laser beams. One more way for experimental proof of plasma creation is an experiment with two-mode laser beams, which are considered as a superposition of two monochromatic waves with commensurable frequencies. We investigate this problem in the framework of the quantum kinetics formulation. The resulting kinetic equation for the distribution function contains a source term describing the vacuum quasiparticle creation in a homogeneous external field. The total quasiparticle number density can be found as a moment of the distribution function. The time dependence of the pair density for the case of one- and two-mode fields and the case of two-mode fields with different frequency coefficient of proportionality are considered.
Pair creation by electromagnetic wave in a collisionless plasma
Andrey V. Filatov, Alexander V. Prozorkevich, Stanislav A. Smolyansky
Electron-positron pair creation by the electromagnetic wave propagating in plasma is investigated in the reference frame moving with the group velocity of the wave. We derive the exact collisionless kinetic equation with non- Markovian source term for the uniform electric field of arbitrary polarization. The back-reaction of plasma is taken into account by means of the dispersion equation. The time dependence of plasma density is studied for the case of linearly polarized field and intensity characteristic for modern optical and planned X-ray lasers. We found that mean pair density created by linearly polarized wave with amplitude Em less than or equal to Ecr negligible in comparison to initial plasma density.
On an effective approximation of the Kantorovich method for calculations of a hydrogen atom in a strong magnetic field
O. Chuluunbaatar, A. A. Gusev, V. L. Derbov, et al.
A new effective method of calculating the wave functions of discrete and continuous spectra of a hydrogen atom in a strong magnetic field is developed based on the Kantorovich approach to the parametric eigenvalue problems in spherical coordinates. The two-dimensional spectral problem for the Schrodinger equation with fixed magnetic quantum number and parity is reduced to a spectral parametric problem for a one-dimensional equation for the angular variable and a finite set of ordinary second-order differential equations for the radial variable. A canonical transformation is applied to approximate the finite set of radial equations by means of a new radial equation describing an open channel. The rate of convergence is examined numerically and illustrated with a set of typical examples. The results are in good agreement with calculations by other authors.
On the Kantorovich approach for calculations of the hydrogen atom states affected by a train of short pulses
O. Chuluunbaatar, A. A. Gusev, V. L. Derbov, et al.
We present theoretical calculations for the evolution of Zeeman states in a train of short electric half-cycle pulses (kicks). For the numerical solution of the corresponding time-dependent Schrodinger equation (TDSE) the high accuracy splitting scheme based on the unitary approximations of the evolution operator is developed. The finite element method is used for determining the spatial form of the solution. The efficiency and stability of the developed computational method is shown for 1D models in the cases of second-, forth-, and sixth-order accuracy with respect to the time step. Numerical calculations for the kicked hydrogen atom in the presence of magnetic field are performed using the scheme of the sixth-order accuracy with respect to a time step and both Galerkin and Kantorovich reductions of the problem with respect to the angular variables. For a particular choice of the electric- and magnetic-field parameters and the initial Zeeman state the corresponding results exhibit a two-state resonance picture.
Strong field atomic ionization dynamics: role of the Coulomb potential studied by means of a model
S. Giraud, B. Piraux, Yu. V. Popov, et al.
We consider the multiphoton ionization of a one-active electron system exposed to an intense low-frequency laser pulse. We describe a model that is aimed at studying the role of the Coulomb potential in a regime where tunneling ionization is assumed to be the dominant ionization mechanism. In particular, we hope to explain why the low energy part of the above-threshold ionization spectrum is not well reproduced by the Keldysh-type theories.
Laser Interferometry and Quantum Optics
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The set of the detection and resolution criteria for a phase modulation microscope
Vladimir A. Andreev, Konstantin V. Indukaev
The principle of operation and design of the phase interferometric microscope is studied. The description of construction and method of work of microscope MIM-2, created according to this principle is given. With the help of this modulation interferometric microscope the vertical resolution up to shares of nanometers and lateral resolution up to tens nanometers is achieved. The simple model of phase relief creation is formulated. With the help of this model the set of the resolution and discovering criteria for some simple objects such as a column, a step, a groove, a long bulge and so on is formulated.
Laser interferometry for study of mutual diffusion in polymer-solvent system
Alexander Abramov, Oleg Dikov, Vladimir Ryabukho, et al.
Optical interferometers for study of mutual diffusion in polymer-solvent systems are considered. The methodology of experiment for the pair of cellulose acetate (as a fiber) - nitromethane (an aprotic and dipolar solvent) is discussed. The kinetics of spatial distribution ofthe medium's refraction index in the process of mass transfer is considered. The kinetics of movement of equal-concentration planes and that of concentration profile changes are determined.
Entanglement of two unidentical atoms through different detunings and thermal noise
The entanglement between two unidentical two-level atoms with different frequencies interacting with one-mode thermal field in lossles cavity has been investigated. The role of detuning in this effect has been carried out.
Dissipative dynamics of nondegenerate two-photon Jaynes-Cummings model
A nondegenerate two-photon Jaynes-Cummings model is investigated where the leakage of photon through the cavity is taken into account. The effect of cavity damping on the mean photon number, atomic populations, field statistics and both field and atomic squeezing is considered on the basis of master equation in dressed-state approximation for initial coherent fields and excited atom.
Creation and destruction of the coherence for quantum systems in regular and stochastic fields
The problem of the coherent states generation with definite parameters for multilevel quantum systems is investigated. The interaction with external environment and stochastic fields can destroy of the coherence. The competition of these processes is considered on a base of Fokker - Planck Equations approach, deriving from master equation for the density matrix of the system. Examples of the coherent states dynamics for two-level atoms in an external stochastic field in the nonideal resonator are considered. Average over the realizations of stochastic fields is performed for the case of white gaussian noise and Kubo - Anderson process. Explicit formulas for transition probabilities, longitudinal and transversal relaxation times and shape of radiation line are obtained.
Spectroscopy and Molecular Modeling
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Comparison of quasipotential and Bethe-Salpeter approaches to the investigation of the two-photon Coulomb interactions
Nataliya A. Boikova, Svetlana V. Kleshchevskaya, Yurij N. Tyukhtyaev
The modification of quasipotential approach to the investigation of binding effects on the fine shift of energy levels of hydrogen-like atoms is applied. The results provide a step towards better agreement between the relativitic calculations of hydrogen-like systems and high-precision spectroscopic measurements.
The biologically active conformations of ligand CCKB receptor
Pavel E. Kuznetsov, Nina B. Kuznetsova, Sergey V. Schulgin, et al.
We analyzed literature data about structures of ligands of CCKB receptor. The structure of the binding site (fragments of the third extracellular loop and the seventh transmembrane helix of CCKB receptor) was determined recently by experiments. We were finding presumable biologically active conformations (BAC) of the ligands by two methods. One of them is based on the fact that the most stable conformations of the biologically active peptide on the phase interface "water-lipophilic medium" are often similar to the BAC. Another method is based on the formation of the stable ligand-receptor complex during the modeling procedure. We used Monte-Carlo method with the fixed geometry of the receptor and the optimized geometry of tetrapeptide cholecystokinin (CCK-4). It has been shown, that the first method should be used to find BAC of antagonists of CCKB receptor. The strategy of the formation of the stable ligand-receptor complex during the modeling procedure can be used for the designing of peptide agonists of CCKB receptor.
Quantum-chemical and experimental modeling of hydrogen peroxide generation in heterogenous aqueous surroundings, which contain dibenzo-p-dioxines or their analogues
Nina B. Kuznetsova, Pavel E. Kuznetsov, Igor A. Vlasov, et al.
A hypothetical molecular mechanism of previously unknown way of toxic action of dibenzo-p-dioxin derivatives has been suggested and demonstrated on the basis of quantum-chemical investigations. The main stages of this process are as follows: protonization of oxygen atom of dioxin ring on the surface of biomembrane; interaction of dioxin with oxygen of oxidized cytochrome P-450; as a result, this xenobiotic becomes a catalyst in the generation of active forms of oxygen (H2O2, O2-, 3O2, etc.). The process may become cyclic if the initial state of dibenzo-p-dioxin is restored. In this case dibenzo-p-dioxines can be considered as carriers of electrons. The hypothesis we are coming up with has been tested by means of comparatively simple experimental models based on the well-known chemical model of cytochrome P-450. Generation of hydrogen peroxide in heterogeneous aqueous media containing dioxanes derivatives has been experimentally proven.
Proton polarizability effect in the hyperfine splitting of the hydrogen atom
R. N. Faustov, I. V. Gorbacheva, A. P. Martynenko
The contribution of the proton polarizability to the ground state hyperfine splitting in the hydrogen atom is evaluated on the basis of isobar model and evolution equations for the parton distributions. The contributions of the Born terms, vector meson exchanges and nucleon resonances are taken into account in the construction of the proton polarized structure functions g1,2 (W,Q2). Numerical value of this effect is equal (2.2 ± 0.8) × 10-6 times the Fermi splitting.
Vibrational spectra, structure, and intermolecular interactions in heterogenic bicomponent systems on the basis of titanium dioxide
Lev M. Babkov, Tamara V. Bezrodnaya, Galina A. Puchkovskaya, et al.
Investigation of the benzophenone (BP)-Ti02 and 4-n-pentyl-4-n'-cyanobiphenyl (5CB)-Ti02 bicomponent mixtures by vibrational spectroscopy and quantum mechanical methods was carried out. IR absorption spectra have been measured in 400-3800 cm-1 region. The structure, energy, electro-optical parameters, frequencies and intensities in the JR spectra for the free benzophenone molecule and for the model of h-complex, which was found to be formed in near-surface layer of the Ti02 nanoparticles, embedded into benzophenone. Also the same parameters were computed for 5CB free molecule and for the model of its H-complex, which may be existent in near surface layer of Ti02 nanoparticles, embedded into 5CB. Calculation was implemented using B3LYP/6-31G(d) method.
Vibrational spectra and structure modelling of the h-complexes in 2-biphenylmethanol using B3LYP/6-31G(d) method
Lev M. Babkov, Jan Baran, Nadejda A. Davydova, et al.
Free 2-biphenylmethanol molecule and hydrogen-bonded complex of its molecules in solid state were optimized using the density functional method (B3LYP/6-31G*). The structure, energy, dipole moments, polarizabilities, frequencies of the normal modes in the harmonic approximation (and in the anharmonic one for the free molecule), and their intensities in JR spectra were calculated. On the basis of the experimental data analysis and computer calculation results, the peculiarities of the crystal structure and dynamics of 2-biphenylmethanol due to H-bonding were clarified. The complete assignment for all vibrational frequencies of crystalline 2 - biphenylmethanol was given.
Spectral characteristics of luminescence centers in alkali halide microcrystals
Julia G. Konyukhova, Vyacheslav I. Kochubey
The experiments on the production of NaCl microcrystals with nickel impurity and double-doped (Ni, In and In, Ca) were carried out. The microcrystals were produced by salting out from aqueous solutions of a sodium salt. In salting out doping concentration did not exceed 1 mole%. The prepared samples were investigated by the luminescence spectroscopy. Spectral characteristics of luminescence of the samples and also changes in the characteristics under the action of ionizing radiation and in room-temperature storage of the irradiated samples were studied. Furthermore, changes in the spectral characteristics of luminescence of the irradiated samples were studied depending on storage period of the initial powder.
Fluorescence in the system Eu(III) - oxytetracycline - co-ligand - sodium dodecylbenzene sulphonate micelles and its analytical application
Sergei N. Shtykov, Tatyana D. Smirnova, Natalja V. Kalashnikova, et al.
Fluorescence enhancement of the Eu3+ - oxytetracycline (OTC) chelate by addition of phenanthroline (Phen) and trioctyiphosphine oxide (TOPO) as well as micelles of anionic, catiomic and nonionic surfactants has been studied. As was found, in the presence of Phen as co-ligand and micelles of dodecylbenzene sulfonate as anionic surfactant the analytical signal increased by a factor of 8.5 and reached maximum value at pH 8.0 ± 0.5. The dynamic concentration range of OTC determination was found to be 8.0 x 10-8 - 4.0 × 10-5 M (R2 = 0.991) and the detection limit 5.3 × 10-8 M (3 σ criterion). The procedure based on europium-sensitized fluorescence has been developed for the determination of OTC in chicken meat with the recovery of 98.0-103.3%.
Calculation of the optical characteristics of CuO nanocomposite by single scattering approximation
The program which calculates the process of light scattering by particles with the Gaussian size distribution by single scattering approximation was written. This program was used to calculate the optical characteristics of light scattering by an optically thin layer of the polystyrene spheres in water. These data were applied to compare two optical schemes, which are used for spectroscopy of the scattering samples. First method uses a wide-angle photodetector and second - uses an integral sphere. It was shown that in spectrophotometric experiments with such samples we must use an integral sphere to obtain a true spectrum. This program was used to calculation the optical characteristics of CuO nanocomposite to investigate
Optical and structural properties of composite material: nanoparticles of CdS involved in high-density polyethylene matrix
M. N. Zhuravleva, V. I. Kochubey, K. V. Zapsis
1 .5 - 2.7 nm size cadmium sulfide (CdS) particles have been synthesized by means of thermal decomposition of precursors with cadmium diacetate and thiourea in the melted high-density polyethylene. The optical and structure properties of produced nanocomposites have been investigated by emission and EXAFS spectroscopy. Identification of the chemical composition has been carried out. The data of X-ray diffraction are evidence of production of cadmium sulfide nanoparticles.
Computer design of tetrapeptide CCK-4 analogues
Pavel E. Kuznetsov, Nina B. Kuznetsova, Sergey V. Schulgin, et al.
In this paper we propose a theoretical method of estimation of biological activity of tetrapeptide cholecystokinin (CCK- 4) analogues according to their structure. The method is based on the prospective mechanism of CCK-4 interaction with CCK-2 receptor. Electron and structural properties of CCK-4 are taken into account. The relationship structure-activity for CCK-4 analogues with the known pharmacological profile have been studied using the model of the ligand-receptor interaction.
Anharmonic analysis of vibrational spectra of substituted uracil
P. M. Elkin, M. A. Erman, O. V. Pulin
An analysis of vibrational spectra of uracil, uracil-C15, thymine is carried out by DFT/B3LYP/6-31G (d) method in the anharmonic approximation.
English as a Communicative Tool in the Scientific Community
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ESP terminology
Svetlana V. Eremina
English for Specific Purposes (ESP) is a part of General English used in the subject specific area. It consists of three main categories, namely, general vocabulary, general academic vocabulary, subject-specific vocabulary units; the last one is considered to be the terms. The general methods and techniques for constructing new and evaluating the present system of terms to be accomplished both by scientists and linguists are discussed.
Stratagems of applied physics
The paper concerns Chinese stratagems which demonstrate practically proved original approach to solving of extraordinary problems. Such questions as what stratagem is, how stratagems may concern physics and how physicists could benefit from stratagem thinking are discussed. Present paper is opening the topic of stratagem thinking application in physics and its main purpose is to attract attention to opportunities of such an application.