Optical characteristics of uniaxial polyester films with the optical axis perpendicular to the surface

The functions of the main indices of refraction n(ν) and absorption κ(ν) of uniaxial thin polyethylene terephthalate films have been calculated by the experimental spectra of frustrated total reflection of s-and p-polarized radiation in the 700–760-cm⁻¹ range. The κ_o(ν) maximum falls at the the 727-cm⁻¹ frequency and the maximum of κ_e(ν) falls at the the 724-and 732-cm^{− 1} frequencies. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 6, pp. 756–759, November–December, 2005.     

Torsional, rotational, and torsional-rotational energy levels of arbitrary molecules with a single internal rotation axis

A program is developed to calculate the torsional-rotational energy levels of multi-atomic molecules containing symmetric or antisymmetric frame and rotor. The torsional-rotational, rotational, and torsional energy levels of the molecules H₂O₂ (asymmetric rotor), C₂H₆ (symmetric rotor), and CH₃NH₂ (asymmetric rotor) are calculated. The value obtained are compared with the corresponding systems of energy levels found by other authors. Ivanovo State Textile Academy, Ivanovo. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, Vol. 42, No. I, pp. 71–80. January, 1999.     

The role of structural and nonstructural water in oxyfluoride K<Subscript>2</Subscript>WO<Subscript>2</Subscript>F<Subscript>4</Subscript> · H<Subscript>2</Subscript>O

X-ray structural and polarization optical investigations have been performed, and birefringence and rotation angles of the optical indicatrix φ _b and φ _c of the K₂WO₂F₄ · H₂O crystal have been measured in the temperature range of 100–600 K. The structure and symmetry of compounds at room temperature have been refined. It has been established that the layered crystal K₂WO₂F₄ · H₂O can exist in two states (A and B) depending on the atmospheric humidity and undergoes the sequence of reversible and irreversible phase transformations G ₃ ↔ G ₂ → G ₁ → G ₀. The sequences of changes in the phase symmetry P [`1]\bar 1 ↔ C2/m → P4/nmm for samples A and m ↔ C2/m → P4/nmm for samples B have been found. The second-order proper ferroelastic phase transition (P [`1]\bar 1 ↔ C2/m) at T ₀₃ = 270–290 K (G ₃ ↔ G ₂) is accompanied by twinning and appearance of the shift deformation x ₆. The crystal system of the substance for the B crystals remains invariable after the second-order phase transition G ₃ ↔ G ₂. The irreversible first-order phase transition G ₂ → G ₁ occurs in a temperature range T ₀₂ ≈ 350–380 K; it is accompanied by the loss of the crystallization water, which then is reduced easily from the atmosphere for a day. The substance decomposes at T ₀₁ ≈ 510 K (G ₁ → G ₀). The distinction between the A and B crystals has been explained by the presence or absence of free water in interlayer spacings.     

A spectroscopic method in studying the dissociation kinetics of hydrogen molecules

The actinometry method was used to study experimentally the kinetics of the formation of hydrogen atoms in a low-pressure glow discharge initiated in a hydrogen-argon mixture. Dependences of the steady-state concentration of hydrogen atoms on current and pressure have been obtained for the ranges i/R=1 to 16 mA/cm and pR=0.7 to 10 Torr·cm, respectively. It has been established that for discharge-activated hydrogen, when the temperature of the system varies only slightly, the recombination frequency parameter v_H=γ_HD_H/Λ² can be used. Ivanovo State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 13–17, May, 1999.     

Ultrasonic-induced synthesis of high surface area colloids CeO2–ZrO2

The nanostructures of high surface area ceria–zirconia colloids have been successfully synthesized via a sonochemical method in the presence of polyethylene glycol 600. Their structural characteristics have been investigated using powder XRD, FESEM, BET surface area, TG, and other techniques. The average size of CeO₂–ZrO₂ nanoparticles is estimated to be 3.7 nm using Debye–Scherrer’s equation. The BET analysis indicates that colloids CeO₂–ZrO₂ have a remarkably high surface area of 226 m² g⁻¹.     

Determination of absorption cross sections for oxygen molecules in the Schumann-Runge band region at high temperatures

We have measured the absorption cross sections of oxygen molecules in oxygen and in an oxygen-argon mixture heated by a shock wave, in the wavelength range 190–250 nm at temperatures of 1500–7000 K, for thermal equilibrium conditions behind the shock wave front. Analysis of the absorption cross sections obtained allowed us to select a data set that adequately describes the absorption characteristics of the electronic transition X³Σ _g ⁻ → B³Σ _u ⁻ for the oxygen molecule. In order to approximate the temperature dependence of these cross sections at a temperature of 1500–4500 K, we chose the function σ(λ, T) = σ₀(λ)(1 − exp (−θ/T)) exp (− n*θ/T) where θ₀ = 1.4·10⁻¹⁷, 1.4·10⁻¹⁷, 1.2·10^{− 17}, and 1.3·10⁻¹⁷ cm², n* = 3.1, 4.1, 5.6, and 7.47 for wavelengths 190, 210, 230, and 250 nm, respectively; θ = 2240 K is the characteristic temperature of the O₂ molecules. The approximation error was 19–25% and did not exceed the experimental error. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 1, pp. 13–17, January–February, 2006.     

Role of charge-transfer complexes in oxygen quenching of excited states of anthracene derivatives in the gas phase

Oxygen quenching of excited triplet and singlet states of gas-phase anthracene and its derivatives that have similar energies of the lower triplet levels but widely different oxidation potentials (0.44 < E_ox < 1.89 V) was studied. Quenching rate constants for singlet (k_S^O2) and triplet (k_T^O2) states in addition to the fraction of oxygen-quenched singlet and triplet states q_{S 1}(T₁^O2 were determined from the decay rates, fluorescence intensities, and delayed fluorescence as functions of oxygen pressure. It was found that k_S^O2 values vary from 2·10⁴ (9,10-dicyanoanthracene) to 1.2·10⁷ sec⁻¹·torr⁻¹ (anthracene, 9-methylanthracene, 2-aminoanthracene) and k_S^O2 values from 5·10² to 1·10⁵ sec⁻¹·torr⁻¹. The k_S^O2 values for anthracene, 9-methylanthracene, and 2-aminoanthracene, which have fast rates of interconversion from S₁ to T₁, are close to the rate constants for gas-kinetic collisions and are independent of the oxidation potentials (E_ox). The quenching rate constants k_S^O2 for the other anthracene derivatives and k_T^O2 for all studied compounds decrease with increasing free energy of electron transfer ΔG_ET, which indicates the important role of charge-transfer interactions in the oxygen quenching of singlet S_1- and triplet T₁ states. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 1, pp. 36–42, January–February, 2008.     

Renormalization in Quantum Field Theory and the Riemann--Hilbert Problem II: The β-Function, Diffeomorphisms and the Renormalization Group

We showed in Part I that the Hopf algebra ℋ of Feynman graphs in a given QFT is the algebra of coordinates on a complex infinite dimensional Lie group G and that the renormalized theory is obtained from the unrenormalized one by evaluating at ɛ= 0 the holomorphic part γ₊(ɛ) of the Riemann–Hilbert decomposition γ₋(ɛ)^{− 1}γ₊(ɛ) of the loop γ(ɛ)∈G provided by dimensional regularization. We show in this paper that the group G acts naturally on the complex space X of dimensionless coupling constants of the theory. More precisely, the formula g ₀=gZ ₁ Z ₃ ^−3/2 for the effective coupling constant, when viewed as a formal power series, does define a Hopf algebra homomorphism between the Hopf algebra of coordinates on the group of formal diffeomorphisms to the Hopf algebra ℋ. This allows first of all to read off directly, without using the group G, the bare coupling constant and the renormalized one from the Riemann–Hilbert decomposition of the unrenormalized effective coupling constant viewed as a loop of formal diffeomorphisms. This shows that renormalization is intimately related with the theory of non-linear complex bundles on the Riemann sphere of the dimensional regularization parameter ɛ. It also allows to lift both the renormalization group and the β-function as the asymptotic scaling in the group G. This exploits the full power of the Riemann–Hilbert decomposition together with the invariance of γ₋(ɛ) under a change of unit of mass. This not only gives a conceptual proof of the existence of the renormalization group but also delivers a scattering formula in the group G for the full higher pole structure of minimal subtracted counterterms in terms of the residue. Received: 21 March 2000 / Accepted: 3 October 2000     

Rheological behaviour of worm-like micelles: Effect of electrostatic interactions

Summary Both linear and non-linear viscoelasticity experiments have been performed in semi-dilute micellar aqueous solutions of ethanediyl-α,ω-bis (dodecylmethylammonium bromide) as a function of solution chloride (NaCl) concentration. The results suggest that both linear and non-linear properties are affected by the electrostatic interactions. In particular, the plateau modulusG′_∞ and the ratioσ _m/G′_∞, whereσ _m represents the plateau value in a stress-shear rate experiment, are enhanced as the electrostatic interactions are screened by addition of salt. The zero-shear viscosity is lowered upon addition of NaCl, due likely to an exchange of the Cl⁻ ions with the Br⁻ counterions. Paper presented at the I International Conference on Scaling Concepts and Complex Fluids, Copanello, Italy, July 4–8, 1994.     

Permittivity and conductivity of triglycine sulfate films on Al/SiO2 and α-Al2O3 substrates

Triglycine sulfate (TGS) films have been prepared by evaporation from a saturated aqueous solution on substrates of fused quartz coated by a layer of thermally deposited aluminum (Al/SiO₂) and white sapphire (α-Al₂O₃) on whose surface interdigital electrodes have been deposited by photolithography. The TGS films have a polycrystalline structure made up of blocks measuring 0.1–0.3 mm (Al/SiO₂) and 0.1 × 1.0 mm (α-Al₂O₃). The polar axis in the blocks is mostly confined to the substrate plane. The temperature dependences of the capacitance and dielectric losses normal to and in the film plane have maxima at the temperature coinciding with that of the ferroelectric phase transition in a bulk crystal, T _c . The low-frequency conductivity G in TGS/Al/SiO₂ structures displays a frequency dispersion described by the relation G ∼ ω ^s (s ≈ 0.82). The conduction can be tentatively ascribed to the hopping mechanism involving localized carriers with a ground state energy of 0.8–0.9 eV. At temperatures above and below T _c , the low-frequency conductivity in TGS/α-Al₂O₃ films operates through a thermally-activated mechanism with an activation energy of 0.9–1.0 eV. At the phase transition, an additional contribution to conductivity appears in TGS/α-Al₂O₃ films with a dispersion G ∼ ω^0.5, which can be associated with domain-wall relaxation.     

Some properties of the newly observed X(1835) state at BES

Recently the BES collaboration has announced the observation of a resonant state in the π⁺π^-η’ spectrum in J/ψ→γπ⁺π^-η’ decay. Fitting the data with a 0^-+ state, the mass is determined to be 1833.7 MeV with 7.7σ statistic significance. This state is consistent with the one extracted from previously reported pp̄ threshold enhancement data in J/ψ→γpp̄. We study the properties of this state using QCD anomaly and QCD sum rules, assuming X(1835) to be a pseudoscalar, and we show that it is consistent with the data. We find that this state has a sizeable matrix element , leading to branching ratios of (2.61–7.37)×10^-3 and (2.21–10.61)×10^-2 for J/ψ→γG_p and for G_p→π⁺π^-η^′, respectively. Combining the calculated branching ratio of J/ψ→γG_p and data on threshold enhancement in J/ψ→γpp̄, we determine the coupling for the G_p–p–p̄ interaction. We finally study the branching ratios of the other J/ψ→γ+three mesons decay modes. We find that J/ψ→γG_p→γ(π⁺π^-η,KKπ⁰) can provide useful tests for the mechanism proposed. PACS 11.55.Hx; 12.39.Fe; 12.39.Mk; 13.25.Gv     

Paramagnetic properties of ion-implanted polymer layers

Films of polyethylene, polyethylene terephthalate, and polyamine-6 implanted with B⁺ and N⁺ ions with an energy of 100 keV are investigated by an EPR method in a dose interval of 1·10¹⁴–1·10¹⁷ cm⁻². It is shown that paramagnetic centers with g=2.0025 formed in the implanted polymers have a nature similar to the nature of paramagnetic centers of pyrolized and initially conducting polymers. Correspondence of the character of the variation in paramagnetic characteristics of the modified polymers to the model proposed earlier for the formation of pyrocarbon “drops” in ion implantation is revealed. The relaxation times for paramagnetic centers in the implanted polymer films are calculated and assumptions are made about the formation of a quasi-two-dimensional electron gas as well as the possibility of magnetic ordering in polymer-film layers modified by high-dosage implantation. The effect of oxygen on the electron states of the implanted polymer specimens is studied. Belarusian State University, 4, Skorina Ave., Minsk, 220050 Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 4, pp. 562–567, July–August, 1998.     

Directional solidification of Ti–49 at.%Al alloy

Ti–49Al (at.%) alloy was directionally solidified in Bridgman-type directional solidification furnace. The specimens were directionally solidified under an argon atmosphere with the different growth rate (V=5–30 μm/s) at a constant temperature gradient (G=12.1 K/mm), and with the different temperature gradient (G=2.8–12.1 K/mm) at a constant growth rate (V=10 μm/s). The dendritic spacings (λ ₁) were measured from both transverse and longitudinal sections of the specimens. The dependence of λ ₁ on the growth rate (V) and temperature gradient (G) were determined by using linear regression analysis. According to the experimental results, the value of λ ₁ decreases with the increase of values of V and G. The experimental results were compared with the current theoretical and numerical models, and similar previous experimental results.     

Roles of the Color Antisymmetric Ghost Propagator in the Infrared QCD

The results of Coulomb gauge and Landau gauge lattice QCD simulation do not agree completely with continuum theory. There are indications that the ghost propagator in the infrared region has strong fluctuation whose modulus is compatible with that of the color diagonal ghost propagator. After presenting lattice simulation of configurations produced with Kogut–Susskind fermion (MILC collaboration) and those with domain wall fermion (RBC/UKQCD collaboration), I investigate in triple gluon vertex and the ghost–gluon–ghost vertex how the square of the color antisymmetric ghost contributes. Then the effect of the vertex correction to the gluon propagator and the ghost propagator is investigated. Recent Dyson–Schwinger equation analysis suggests the ghost dressing function G(0) = finite and no infrared enhancement or α _G  = 0. But the ghost propagator renormalized by the loop containing a product of color antisymmetric ghost is expected to behave as with with α _G = 0.5, if the fixed point scenario is valid. I interpret the α _G  = 0 solution should contain a vertex correction. The infrared exponent of our lattice Landau gauge gluon propagator of the RBC/UKQCD is α _D  = − 0.5 and that of MILC is about − 0.7. A possible interpretation of the origin of the fluctuation is given.     

Determination of the neutron electric form factor from the reaction 3 He(e,e'n) at medium momentum transfer

The electric form factor of the neutron G_En has been determined in double polarized exclusive ³ He(e,e'n) scattering in quasi–elastic kinematics by measuring asymmetries A _⊥, A _∥ of the cross section with respect to helicity reversal of the electron, with the nuclear spin being oriented perpendicular to the momentum transfer q in case of A_⊥ and parallel in case of A_∥. The experiment was performed at the 855 MeV c. w. microtron MAMI at Mainz. The degree of polarization of the electron beam and of the gaseous ³ He target were each about 50%. Scattered electrons and neutrons were detected in coincidence by detector arrays covering large solid angles. Quasi–elastic scattering events were reconstructed from the measured electron scattering angles ϑ_e, φ_e and the neutron momentum vector p _n ^′ in the plane wave impulse approximation. We obtain the result <G _En>_{(0.27 < Q2c2/GeV2 < 0.5)}= 0.0334 ± 0.0033_stat± 0.0028_syst which is averaged over the indicated range of Q ², the squared momentum transfer. This G _En value is significantly smaller than measured from the D(e,e'n) reaction under similar kinematical conditions. To what extent final state interactions in ³He quench the G _En result is subject of calculations currently in progress elsewhere. Received: 29 April 1999     

Kinetics of photon generation and propagation in a scintillation layer

Experimental results of an investigation of the kinetics of photon generation and propagation in a scintillation layer (n-terphenyl in polystyrene) are presented in this paper for the case of relativistic μ-meson passage through the layer. The duration of the photon emission Δt_em has been measured as a function of the scintillation layer thickness (l=0.05–0.5 m). The total duration of the photon emission and exit from the scintillation layer Δt_tot measured with a side coating having diffuse light reflection coefficient ρ=0.9 and 0.95 is given. A kinetic model of the photon generation and propagation in the scintillation layer is described. Satisfactory agreement of the expected values of Δt_em and Δt_tot with the exeeriment is indicated. Ivanovo State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 73–77, June, 1999.     

Kinetics of the b{su1}Σ{sk{su\s+}/{in{itg}}→\ga{su1}\gD{in{itg}} fluorescence of molecular oxygen in solutionsfluorescence of molecular oxygen in solutions

The kinetics of sensitized fluorescence of O₂ has been recorded for the first time in solutions at transition from the second singlet excited state b{su1}Σ{sk{su\s+}/{in{itg}} to the first excited state \ga{su1}\gD{in{itg}} (b→a. We measured the quantum yield of the b→a-fluorescence at γ≈1.93 μm and assessed its probability with respect to the a→ X-phosphorescence at 1.27 μm. We show that the lifetime of the b→a-fluorescence (105 nsec for CCl₄ and 140 nsec for CS₂) becomes much shorter on addition of solvents with large frequencies of intramolecular vibrations. The measured radiative velocity constant of the b→a-transition K_b→a is by three orders of magnitude larger than for the phosphorescence (≈1.27 μm) of the a→X-transition from the first singlet to the ground triplet state. The method of recording IR fluorescence is promising for determining O₂ in solutions and biosystems. Institute of Molecular and Atomic Physics of the National Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 1, pp 5–8, January–February, 1998.     

Contributions of high-spin resonances to the reaction γp → ηp for photon energies above 2 GeV

Based on new experimental data obtained for photon energies in the range 2–3 GeV, the contributions and properties of heavy high-spin resonances to the amplitude of the process γp → ηp obtained by an earlier constructed model have been corrected. It has been shown that this process is related to the G₁₇(2190) and H₁₉(2220) resonances. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 87–90, March, 2006.     

Special features of recording IR spectra of MFTIR of fibrous materials

We investigated the influence exerted by the conditions of preparation of specimens of fibrous materials made of polyethylene terephthalate and triacetate threads and fabrics and the conditions of recording IR spectra of modified frustrated total internal reflection (MFTIR) on the reproducibility of spectral characteristics. We found that the area of actual contact of fibrous meterials with a reflecting prism and the reproducibility of spectral characteristics can be considerably increased by applying preliminary pressing and increasing the pressure of clamping the materials to the prism. We determined the optimum values of the parameters for preparing specimens and recording MFTIR spectra that make it possible to carry out, with sufficient accuracy, spectrophotometering of fibrous specimens made of polyethylene terephthalate and triacetate fabrics and threads. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 103–107, January–February, 1997.     

Thermal analysis of InP-based quantum cascade lasers for efficient heat dissipation

We have theoretically investigated the thermal characteristics of double-channel ridge–waveguide InGaAs/InAlAs/InP quantum cascade lasers (QCLs) using a two-dimensional heat dissipation model. The temperature distribution, heat flow, and thermal conductance (G _th) of QCLs were obtained through the thermal simulation. A thick electroplated Au around the laser ridges helps to improve the heat dissipation from devices, being good enough to substitute the buried heterostructure (BH) by InP regrowth for epilayer-up bonded lasers. The effects of the device geometry (i.e., ridge width and cavity length) on the G _th of QCLs were investigated. With 5 μm thick electroplated Au, the G _th is increased with the decrease of ridge width, indicating an improvement from G _th=177 W/K⋅cm² at W=40 μm to G _th=301 W/K⋅cm² at W=9 μm for 2 mm long lasers. For the 9 μm×2 mm epilayer-down bonded laser with 5 μm thick electroplated Au, the use of InP contact layer leads to a further improvement of 13% in G _th, and it was totally raised by 45% corresponding to 436 W/K⋅cm² compared to the epilayer-up bonded laser with InGaAs contact layer. It is found that the epilayer-down bonded 9 μm wide BH laser with InP contact layer leads to the highest G _th=449 W/K⋅cm². The theoretical results were also compared with available obtained experimentally data.