OPTICAL-OPTICAL DOUBLE-RESONANCE EXCITATION SPECTRA OF THE (6d)1Πg, (7d)1Πg HIGH-LYING RYDBERG STATES IN Na2

Two ¹Π_g states of Na₂ for v≤13 have been observed by using optical-optical double resonance (OODR) fluorescence excitation spectroscopy. The intermediate levels in B¹Π_u state are identified by the numerical calculations with the molec-ular constants for B¹Π_u←X¹Σ_g⁺ transitions and confirmed by the complemen-tary A¹Σ_g⁺←X¹Σ_g⁺ polarization spectra. Absolute vibrational numberings of the (6d)¹Π_g and (7d)¹Π_g states are determined by comparing the experimental OODR excitation intensities with the simulated Franck-Condon factors. The Dnnham coef-ficients and the Rydberg-Klein-Rees (RKR) potential energy curves of the (6d)¹Π_g, (7d)¹Π_g states are reported.     

Determination of amorphous layers on thick film Nasicon in dependence on different sintering processes

In thick film gas sensors Nasicon is used as a solid electrolyte with high Na⁺ ionic conductivity. Sensors like CO₂, O₂, Pt ▮ Na₂CO₃, BaCO₃ ∥ NASICON [Pt]_glass, O₂, CO₂ are suitable to measure the CO₂-concentration over 5 orders of magnitude. To characterize the screen printed Nasicon as a main component of such sensors grazing incidence diffractometry (GID), SEM, impedance spectroscopy and dc polarization measurements are performed in order to improve the long-term stability. The sintering process of the thick film influences the chemical surface composition of Nasicon and as a consequence the response of the sensor. Nasicon films sintered at temperatures between 1070 and 1210 °C show an amorphous layer increasing up to 1.1 μm thickness on the surface. Impedance measurements show, that cells using in such a way prearated Nasicon are responsible for water vapour. Paper presented at the 1st Euroconference on Solid State Ionics, Zakynthos, Greece, 11 – 18 Sept. 1994     

Solvent effects on the S0→S2 absorption spectra of β-carotene

Absorption spectra of β -carotene in 31 solvents are measured in ambient conditions. Solvent effects on the 0--0 band energy, the bandwidth, and the transition moment of the S₀ → S₂ transition are analysed. The discrepancies between published results of the solvent effects on the 0--0 band energy are explained by taking into account microscopic solute-solvent interactions. The contributions of polarity and polarizability of solvents to 0--0 band energy and bandwidth are quantitatively distinguished. The 0--0 transition energy of the S₂ state at the gas phase is predicted to locate between 23000 and 23600~cm^-1.     

Investigations of spectroscopic parameters and molecular constants for X1Σg+, w3Δu, and W1Δu electronic states of P2 molecule

The potential energy curves (PECs) of three low-lying electronic states (X¹Σ_g⁺, w³Δ_u, and W¹Δ_u)of P₂ molecule are investigated using the full valence complete active space self-consistent field (CASSCF) method followed by the highly accurate valence internally contracted multireference configuration interaction (MRCI) approach in conjunction with the correlation-consistent basis set in the valence range. The PECs of the electronic states involved are modified by the Davidson correction and extrapolated to the complete basis set (CBS) limit. With these PECs, the spectroscopic parameters of the three electronic states are determined and compared in detail with the experimental data. The comparison shows that excellent agreement exists between the present results and the available experimental data. The complete vibrational states are computed for the w³Δ_u, and W¹Δ_u electronic states when the rotational quantum number J equals zero and the vibrational level G(v), the inertial rotation constant B_v, and the centrifugal distortion constant D_v of the first 30 vibrational states are reported, which accord well with the experimental data. The present results show that the two-point extrapolation scheme can obviously improve the quality of spectroscopic parameters and molecular constants.     

Spectroscopic investigations on NO+(x1∑+,a3∑+,A1Ⅱ) ion using multi-reference configuration interaction method and correlation-consistent sextuple b

Three low-lying electronic states (x¹∑⁺,a³∑⁺,and A¹Ⅱ) of NO⁺ ion are studied using the complete active space self-consistent-field (CASSCF) method followed by highly accurate valence internally contracted multi-reference configuration interaction (MRCI) approach in combination of the correlation-consistent sextuple basis set augmented with diffuse functions, aug-cc-pV6Z. The potential energy curves (PECs) of the NO⁺(x¹∑⁺,a³∑⁺,A¹Ⅱ) are calculated. Based on the PECs, the spectroscopic parameters R_e, D_e, ω_e, ω_eχ_e, α _e, B_e, and D₀ are reproduced, which are in excellent agreement with the available measurements. By numerically solving the radial Schrödinger equation of nuclear motion using the Numerov method, the first 20 vibrational levels, inertial rotation and centrifugal distortion constants of NO⁺(x¹∑⁺,a³∑⁺,A¹Ⅱ) ion are derived when the rotational quantum number J is equal to zero (J = 0) for the first time, which accord well with the available measurements. Finally, the analytical potential energy functions of these states are fitted, which are used to accurately derive the first 20 classical turning points when J = 0. These results are compared in detail with those of previous investigations reported in the literature.     

X-ray and luminescent analysis of finely dispersed β-FeSi2 films formed in Si by pulsed ion-beam treatment

Finely dispersed β-FeSi₂ films were formed by implanting Fe⁺ ions with an energy of 40 keV and a dose of 1×10¹⁶ cm⁻² in Si single crystals, followed by nanosecond pulsed ion-beam treatment. The results of glancing incidence x-ray diffraction indicate the formation of a highly grain-oriented film consisting of inclusions of the iron disilicide phase (β-FeSi₂) with a grain size of approximately 40 nm surrounded by a polycrystalline Si matrix. The photoluminescence spectroscopy data reveal that the photoluminescence signal with a peak around 1.56 μm, which is observed up to 210 K, is associated with direct interband transitions in β-FeSi₂ and not with the contribution from the dislocation-induced line D1. __________ Translated from Fizika Tverdogo Tela, Vol. 43, No. 9, 2001, pp. 1569–1572. Original Russian Text Copyright ? 2001 by Bayazitov, Batalov, Terukov, Kudoyarova.     

Luminescence and lasing properties of neodymium- and uranium-activated inorganic laser liquids

An attempt was made to describe and show the possibilities of new inorganic neodynium- and uranium-activated laser liquids: SO₂-GaCl₃-NdCl₄; SO₂Cl₂-GaCl₃-NdCl₃-UO₂Cl₂; POCl₂-MCl_n-NdCl₃-UO₂Cl₂ for development and synthesis of direct nuclear reaction-excited lasers. Luminescence data presented in the work were used to calculate the luminescence parameters of the laser liquids such as oscillator strengths f, probability of spontaneous radiation A, intermultiplet luminescence branching coefficient β, cross-section for induced radiation σ, luminescence decay time τ, quantum yield η, and others. It is shown that the oscillator strengths of the normal absorption bands of Na³⁺, which play the main part in the pumping processes, exceed the oscillator strengths of Na³⁺ for aqueous and many other nonaqueous systems. In the luminescence excitation spectra of the Na³⁺ ion, bands are isolated in the range 400–1000 nm atλ _rec =1.06 μm. With excitation, luminescence occurs through the⁴F_3/2→⁴I_{9/2,11/2.13/2} channels. Luminescence spectral data are related to the lasing parameters. The threshold lasing energy is∼18 J/cm³. For a resonator with mirros h₁=100% and h₂=20, 40, 56, and 80%, the lasing energy is∼20–120 MJ/cm³ in the pumping energy range 18–180 J/cm³. The differential efficiency is ∼0.2% The substantial angular radiation divergence (θ∼4·10⁻² rad) and strong thermostatic distortions that occur in the active element (dn/dT≈−1.9·10⁻⁴K⁻¹) are a disadvantage of laser liquids. It is shown that operation of neodymium- and uranium-activated inorganic liquid lasers is stable under the present conditions. A. I. Gertsen Russian State Pedagogical University, Moika Embankment, 48, St. Petersburg, 191186, Russia. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 5, pp. 607–619, September–October, 1997.     

The dynamics of accumulation of electrically active radiation defects on implantation of graded-band-gap HgCdTe films grown by MBE

The dynamics of accumulation of electrically active radiation defects under ion doping of epitaxial Cd _x Hg _1−x Te films is studied for various distributions of film composition in the implantation region. The epitaxial films were irradiated by boron ions at room temperature in the continuous regime, with the dose ranging within 10¹¹−3·10¹⁵ cm⁻², energy — 20–150 keV, and ion current density — j = 0.001–0.2 μA·cm⁻². It is found that the natural logarithm of the introduction rate of electrically active radiation defects linearly depends on the epitaxial-film composition in the range of mean projected path of implanted ions. An analysis of the experimental data shows that the dynamics of accumulation of electrically active radiation defects is determined by the epitaxial-film composition in the implantation region. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 25–28, September, 2006.     

HIGH-RESOLUTION ANALYSIS OF THE ν2+2ν3 BAND OF HDO

The Fourier transform spectrum of the ν₂+2ν₃ band of the HDO molecule was recorded with a resolution of 0.02 cm^-1. The spectrum was rotational analysed and the spectroscopic parameters of the (0,1,2) state were estimated in terms of Watson's effective rotational Hamiltonian model and also the model in the Padé-Borel approximation form. They reproduce the upper energy levels with an accuracy close to the experimental uncertainty of 0.001 cm^-1.     

间氟溴苯分子240 nm紫外光解动力学

The photodissociation dynamics of m-bromofluorobenzene has been experimentally investigated at around 240 nm using the DC-slice velocity map imaging technique. The kinetic energy release spectra and the recoiling angular distributions of fragmented Br(²P_3/2) and Br(²P_1/2) atoms from photodissociation of m-bromofluorobenzene have been measured at different photolysis wavelengths around 240 nm. The experimental results indicate that two dissociation pathways via (pre-)dissociation of the two low-lying ¹ππ^* excited states dominate the production process of the ground state Br(²P_3/2) atoms. Because of the weak spin-orbit coupling effect among the low-lying triplet and singlet states, the spin-orbit excited Br(²P_1/2) atoms are mainly produced via singlet-triplet state coupling in the dissociation step. The similarity between the present results and that recently reported for o-bromofluorobenzene indicates that the substitution position of the fluorine atom does not significantly affect the UV photodissociation dynamics of bromofluorobenzenes.     

Numerical study on characteristics of nitrogen discharge at high pressure with induced plasma

Based on the fluid theory of plasma, a model is built to study the characteristics of nitrogen discharge at high pressure with induced argon plasma. In the model, the spices such as electron, N₂⁺, N₄⁺, Ar⁺, and two metastable states (N₂ (A³∑_u⁺), N₂ (a¹∑_u^-)) are taken into account. The model includes particle's continuity equations, electron's energy balance equation, and Poisson equation. The model is solved with a finite difference method. The numerical results are obtained and used to investigate the effect of time taken to add nitrogen gas and initially-induced argon plasma pressure. It is found that lower speeds of adding the nitrogen gas and varying the gas pressure can induce higher plasma density, and inversely lower electron temperature. At high-pressure discharge, the electron density increases when the proportion of nitrogen component is below 40%, while the electron density will keep constant as the nitrogen component further increases. It is also shown that with the increase of initially-induced argon plasma pressure, the density of charged particles increases, and the electron temperature as well as the electric field decrease.     

Structural features of aluminium alloy 1441 irradiated by Ar+ ions

Using electron microscopy it was found that irradiation of clad cold-worked specimens made of commercial aluminium-lithium alloy 1441 by the Ar ⁺ ions of energy 40 keV at low doses of irradiation (10¹⁵ cm⁻², irradiation time 1 s, T < 70 °C) and ion-current density of about 100 μA/cm² results in the transformation of the cellular structure formed in the alloy under deformation. As the dose of irradiation is increased up to 10¹⁶ cm⁻², a transition from a cellular to a subgrain structure close to a polygonal one is observed. The efficiency of the process is increased with ion-current density. Furthermore, under ion irradiation at increased ion-current densities, the β′(Al ₃ Zr) and Al ₈ Fe ₂ Si particles present in the deformed alloy dissolve, and disperse particles of a new Al ₂ LiMg phase of platelet shape are formed. The changes in the dislocation structure and phase composition in alloy 1441 are observed several seconds after irradiation not only in the surface layer adjacent to the ion incorporation band but also through the thickness of the specimen tens of thousands times greater than ion projective ranges. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 73–81, February, 2007.     

Comparison of optical properties and mechanical/electrical degradation of some low density polyethylene-and polypropylene-based polymer blends

In this study, the optical properties as well as mechanical and electrical degradation of low-density polyethylene (LDPE)/polypropylene fiber (PP fiber) (10–50% PP fiber), polypropylene (PP)/PP fiber (10–50% PP fiber), and LDPE/diamond (0.1–3% diamond) blends, which are prepared by hot pressing method, with changing thicknesses ranging from 30 to 225 μm, are compared. The spectra, in the wavelength range 200–2500 nm, are examined. Based on optical absorption spectra obtained, Tauc graphs are plotted. Determined values of the direct optical energy gap (E _d ^opt ), the indirect optical energy gap (E _i ^opt ), the width of the band (ΔE), and ultraviolet transmittance (T_UV) are listed. The direct E _d ^opt and indirect E _i ^opt values for organic blends are in the range of 3.10–3.17 eV and 1.52–2.99 eV; for inorganic blends they are 1.80–4.13 eV and 1.55–4.7 eV respectively. The electrical strength (ε) and the mechanical tension (σ) have been investigated, and graphs (the dependence of the electrical life time log τ_ε on ε) are given. The experimental results are analyzed from the viewpoint of the validity of the thermofluctuation theory. LDPE and LDPE/0.5% diamond composite parameters consecutively changed: σ from 68 to 82 MPa, ε from 60·10⁶ to 85·10⁶ V/m, mechanical lifetime τ_σ from 10 to 1.5·10⁵ sec, electrical lifetime τ_ε from 2· 10³ to 2·10⁵ sec, and structure-sensitive parameters γ and χ — from 1.48 to 1.18 (J)MPa/mole and from 0.97 to 0.70 (J)Vm⁻¹/mole respectively. The values of mechanical and electrical durability were observed to increase by 20 and 41%, respectively, for LDPE/0.5% diamond composite. Published in Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 5, pp. 677–683, September–October, 2007.     

CuH分子A1∑+态的寿命和预解离研究

A combined cavity ringdown (CRD) and laser induced fluorescence (LIF) spectroscopic study on the A¹∑⁺-X¹∑⁺ transition of CuH has been presented.The CuH molecule,as well as its deuterated isotopologue CuD,are produced in a supersonic jet expansion by discharging H₂(or D₂) and Ar gas mixtures using two copper needles.Different profiles of relative line intensities are observed between the measured LIF and CRD spectra,providing an experimental evidence for the predissociation behavior in the A¹∑⁺ state of CuH.The lifetimes of individual upper rotational levels are measured by LIF,in which the J''-dependent predissociation rates are obtained.Based on the previous theoretical calculations,a predissociation mechanism is concluded due to the strong spin-orbit coupling between the A¹∑⁺ state and the lowest-lying triplet ³∑⁺ state,and a tunneling effect may also be involved in the predissociation.Similar experiments are also performed for CuD,showing that the A¹∑⁺ state of CuD does not undergo a predissociation process.     

Registration of hydrogen-like leptonic bound states ( e-μ+) and ( e+μ-) in reactions of high-energy scattering of polarized electrons and positrons by nuclei with Z ～ 100 and analysis of CPT invariance

The cross-sections for the reactions of muonium (anti-muonium) production in the high-energy electron (positron) scattering by nuclei e ^-(e ⁺) + Z↦Z + M ⁰(ˉM) + μ^-(μ⁺) are calculated in dependence on energy and polarization of the initial electron (positron) and polarization of the final μ^-(μ⁺)-meson. Since this is a coherent phenomenon the cross-sections are proportional to Z². For Z ∼ 100, due to the factor Z², the cross-sections are large enough to be measured at the energies available for the HERA Collider at DESY. The results are discussed in connection with a test of CPT invariance. Received: 24 September 2002 / Accepted: 12 March 2003 / Published online: 27 May 2003     

Ab initio calculation of accurate dissociation energy, potential energy curve and dipole moment function for the A1∑ + state 7LiH molecule

The reasonable dissociation limit of the A¹∑⁺ state $^{7}$LiH molecule is obtained. The accurate dissociation energy and the equilibrium geometry of this state are calculated using a symmetry-adapted-cluster configuration-interaction method in complete active space for the first time. The whole potential energy curve and the dipole moment function for theA¹∑⁺ state are calculated over a wide internuclear separation range from about 0.1 to 1.4\,nm. The calculated equilibrium geometry and dissociation energy of this potential energy curve are of R_{\e}=0.2487\,nm and D_{\e}=1.064\,eV, respectively. The unusual negative values of the anharmonicity constant and the vibration-rotational coupling constant are of \textit{\omega }_{\e}\textit{\chi }_{\e}=--4.7158cm^{ - 1} and \textit{\alpha }_{\e}=--0.08649cm^{ -1}, respectively. The vertical excitation energy from the ground to the A¹∑⁺ state is calculated and the value is of 3.613\,eV at 0.15875nm (the equilibrium position of the ground state). The highly anomalous shape of this potential energy curve, which is exceptionally flat over a wide radial range around the equilibrium position, is discussed in detail. The harmonic frequency value of 502.47cm¹ about this state is approximately estimated. Careful comparison of the theoretical determinations with those obtained by previous theories about the A¹∑⁺ state dissociation energy clearly shows that the present calculations are much closer to the experiments than previous theories, thus represents an improvement.     

Mechanooptical investigations of polyimide films exposed to electrons,mechanical loads,and temperatures

Joint effect of high-energy electrons, mechanical loads, and temperature on polyimide films of thicknesses in the range 30–130 μm is investigated. The films were preliminary irradiated by electrons in air using an éLU-6 linear accelerator with energy of 2 MeV and doses D = 1, 5, 10, 20, 30, 40, and 100 MGy and then subjected to uniaxial mechanical tension at temperatures (T) from 293 to 593 K. It is established that at T = 293–450 K and D = 20–40 MGy, the mechanical load causes almost the same deformations (ε_{l max}) of nonirradiated and irradiated samples; at T = 450–550 K, deformations of films sharply increase, and the character of their dependence changes. The ε_{l max} value of the initial sample increases almost linearly with temperature by a factor of 10, whereas the character of changing ε_{l max}(T) of the irradiated films is more complex, and its value increases approximately by a factor of 4. For T > 500 K, the deformation reaches limiting values. Irradiation increases the intensity of IR-spectra by 2–6 times and essentially increases the widths of absorption bands at 720, 1380, and 1775 cm⁻¹, which is caused by the formation of hydrogen bonds and cycles with nitrogen as well as by the formation of nitrogen oxides. External loading applied to film rupture causes an increase in the EPR signal amplitude from 3·10³ to 5·10³, which is connected with an increased concentration of radicals =N-H and-NH ₂. The electron irradiation of the polyimide films with their subsequent mechanical loading causes the spectrum lines to displace from 3475.0 to 3512.5 cm⁻¹ with simultaneous reduction of the signal amplitude from 6·10³ to 4·10³. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 52–58, February, 2007.     

大气中硫酸生成反应势能面的量子化学研究

A new potential energy surface (PES) for the atmospheric formation of sulfuric acid from OH+SO₂ is investigated using density functional theory and high-level ab initio molecular orbital theory. A pathway focused on the new PES assumes the reaction to take place between the radical complex SO₃·HO₂ and H₂O. The unusual stability of SO₃·HO₂ is the principal basis of the new pathway, which has the same final outcome as the current reaction mechanism in the literature but it avoids the production and complete release of SO₃. The entire reaction pathway is composed of three consecutive elementary steps:(1) HOSO₂+O₂→SO₃·HO₂, (2) SO₃·HO₂+H₂O→SO₃·H₂O·HO₂, (3) SO₃·H₂O·HO₂→H₂SO₄+HO₂. All three steps have small energy barriers, under 10 kcal/mol, and are exothermic, and the new pathway is therefore favorable both kinetically and thermodynamically. As a key step of the reactions, step (3), HO₂ serves as a bridge molecule for low-barrier hydrogen transfer in the hydrolysis of SO₃. Two significant atmospheric implications are expected from the present study. First, SO₃ is not released from the oxidation of SO₂ by OH radical in the atmosphere. Second, the conversion of SO₂ into sulfuric acid is weakly dependent on the humidity of air.     

Review of theoretical gain-optimization studies in 10.6µm CO2-N2 gasdynamic lasers

A comprehensive theoretical analysis of optimization of gain in CO₂-N₂ gasdynamic laser employing wedge or conical or hyperbolic nozzles with either H₂O or He as the catalyst is presented. After a review of previous work, the usual governing equations for the steady inviscid quasi-one-dimensional flow in a supersonic nozzle of a gasdynamic laser are used to obtain similar solutions for the various flow quantities, which variables are subsequently used to optimize the small-signal gain on theP(20) line of the (001) → (100) transition of CO₂ at wavelength 10.6μm. The corresponding optimum values like reservoir pressure and temperature and nozzle area ratio also have been predicted and presented in the form of graphs. The analysis predicts that employing of 2D-wedge nozzle results in higher gain values and the CO₂-N₂-H₂O gasdynamic laser employing 2D-wedge nozzle is operationally the best laser system for which the optimum value as high as 3.1 m⁻¹ gain can be obtained.     

In-situ formation of thin-film like β′'-alumina layers on α-alumina substrates

The in-situ formation of layers consisting of β′'-alumina on high purity polycrystalline α-alumina substrates was investigated. The direct synthesis of sodium and potassium β′'-alumina layers was possible in a mixture of uncalcined powders of stoichiometries close to the β′'-alumina phase in a temperature-time window between 1200 and 1400 °C and 1 h to 12 h. These materials were employed for ion exchange processes in order to obtain Li⁺, H₃O⁺ and Ca²⁺-β′'-alumina modifications, which could not be synthesized by the direct method. The resulting materials were characterized by SEM/EDX, XRD, DTA and IS. The obtained β′'-alumina layers show the same properties as polycrystalline monolithic ceramics but are available as thin films of thicknesses between 4 and 25 μm on insulating, well defined substrate materials. Paper presented at the 4th Euroconference on Solid State Ionics, Renvyle, Galway, Ireland, Sept. 13–19, 1997