Anharmonic resonances in the vibrational spectra of pyrazine

The quartic force field of pyrazine has been calculated in the B3LYP/6-31G(d) hybrid density-functional approximation. Based on the results of this calculation, the total IR (250–3800 cm^–1) and Raman (400–3200 cm^–1) spectra of pyrazine have been interpreted with consideration for the Fermi and Darling-Dennison resonances and their spectral manifestations. A precision method is proposed for anharmonic analysis of the vibrational states of polyatomic molecules on the basis of consideration of their theoretical anharmonicity constants in combination with the corresponding experimental frequencies. The method of linear scaling of frequencies has been theoretically substantiated.__________Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 1, pp. 13–22, January–February, 2005.     

Shift Coefficients and Self-Pressure Broadening of H2 16O Lines in the Range 1950–2750 cm−1

Experimental values of the shift coefficient and self-pressure broadening by the own pressure have been determined for some spectral lines of water vapor in the range 1950–2750 cm^–1. A comparison with the calculated data obtained on the basis of the Robert–Bonamy method has been performed. A satisfactory agreement between the theory and experiment has been obtained.     

Analysis of the stability of semiconducting five-component solid solutions of III-V compounds

The model of regular solutions has been used to obtain expressions for calculating the boundaries of the region of spinodal decomposition for five-component solid solutions of III-V compounds. The stability region of the solid solution Al_x1Ga_x2In_1–x1–x2P_yAs_1–y has been estimated.Moscow Institute of Electronic Engineering. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 11–13, December, 1993.     

Trace Detection of Low Concentrations of Ozone Using a CO<Subscript>2</Subscript> Laser with Automatic Tuning over the Spectrum

A technique of detection of ozone, using a CO₂ laser with rapid automated tuning over 8–10 generation lines in the 9.4–9.6-µm spectral range, has been developed. Its experimental verification has shown a higher accuracy of detecting low concentrations of O₃ in comparison with the traditional technique of differential absorption on two lines (on-line and off-line). Using the technique suggested, the content of ozone in the vicinity of city roads with heavy traffic has been measured.__________Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 2, pp. 251–255, March–April, 2005.     

Calculation and study of the IR absorption spectrum of hydantoin

The IR absorption spectrum of hydantoin has been obtained in the range 400–3500 cm^–1, and the normal-vibration frequencies are calculated on the basis of the mechanical model. The spectrum is interpreted.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, Vol. 12, No. 6, pp. 116–120, June, 1969.     

Bromoacyl Analogs of Pyrene–Containing Phosphatidylcholine as New Fluorescent Lipid Probes with Intramolecular Quenching

Two new derivatives of phosphatidylcholine with an intramolecularly quenched fluorescence, namely, 1––bromoundecanoyl–2–[4–(pyren–1–yl)butyroyl]–sn–glycero–3–phosphocholine (BPPhC) and 1–(9,10–dibromostearoyl)–2–[4–(pyren–1–yl)butyroyl]–sn–glycero–3–phosphocholine (DBPPhC), have been obtained by replacing acyl chains by residual pyrenebutyric and bromine–labeled fatty acids. Their structure has been verified by the ¹H–NMR method and the spectral properties have been characterized in media of different polarity with the aid of absorption and fluorescent spectroscopy. It has been established that when BPPhC and DBPPhC are included in liposomes, the intensity of their fluorescence changes markedly as a function of the physical state of the bilayer, which makes it possible to use the compounds obtained as lipid probes for investigating the properties of biological and artificial membranes.     

Investigation of the Structure of Polyelectrolyte–Micelle Complexes by the Luminescing Probe Technique

Using the luminescing probe technique, we have investigated the process of the formation of polyelectrolyte–micelle complexes and their structure. We have studied the interaction between macroions on the micelle–polyelectrolyte boundary. It has been established that, when the complex is formed in this way, the polarity in the surface layer of the micelle is increased. On increase in the concentration of polyelectrolyte and decrease in the length of its chain the micelle–polyelectrolyte complex becomes stabilized.     

Radical-Recombination Luminescence of the Uranyl Nitrate Complex in the Adsorbed State

We have investigated the luminescence of uranyl nitrate molecules on the surface of powdery SiO₂ upon excitation by UV light (PhL) and hydrogen atoms (radical-recombination luminescence (RRL)). It has been found that the PhL and RRL spectra have a clearly defined vibrational structure. The luminescence peaks of the adsorbed UO₂ ^2– ion are characterized by a systematic longwave shift from the same peaks of crystalline uranyl nitrate (by 230–430 cm^–1 at 130 K). Moreover, in the adsorption centers the vibration frequencies of UO₂ ^2– are 20–80 cm smaller than in crystalline salt and the RRL bands are 150–350 cm^–1 (130 K) wider than the corresponding PhL bands.     

Densities and velocity distributions of atomic hydrogen and carbon,measured by laser-induced fluorescence with frequency tripling into the vacuum UV

By focussing a commercial dye laser pumped with a XeCl excimer laser into phase matched Xe-A or Kr-A gas mixtures, radiation at the third-harmonic frequency has been generated in the wavelength regions: 1142–1165, 1178–1186, 1203–1224, and 1268–1290 Å. VUV powers up to about 200 W have been detected by a calibrated Au-photodiode. The vacuum uv radiation has been used for the fluorescence excitation of H and C atoms produced by thermal dissociation or by a gas discharge. Absolute densities have been derived by a comparison of fluorescence intensities with intensities from Rayleigh scattering in argon. As a further application, velocity distributions of C atoms sputtered from a graphite target by 1.5 keV argon ions have been measured. These data are in good agreement with a Thompson distribution corresponding to a surface energy of 8.2 eV.     

Strong-interaction approximation in the theory of second harmonic generation of intense short laser pulses

The method of strong interaction of nonlinear waves has been developed to analyse the second harmonic generation of intense laser radiation in the transient regime. Analytic solution for frequency conversion efficiency – taking into account the pump radiation depletion, influence of phase mismatch, dispersion of group velocities and higher nonlinearities – has been first obtained. A comparison of theoretically derived results and known experimental data has been conducted, and a general agreement of these results has been obtained. The optimal conditions of the second harmonic generation of neodymium laser radiation into femtosecond pulse duration range have been determined.     

High-T c superconductivity in the Bi-Sr-Ca-Cu-O system

Superconductivity with transitions near 80 K and 110 K has been observed in sintered samples of the system Bi–Ca–Sr–Cu–O. The samples were prepared from mixed powders of the oxides or carbonates of the metallic elements. It was found that the heat treatment has to be restricted to a narrow temperature range near 800 °C to obtain optimum samples with respect to superconductivity. The best samples show two transitions of equal height at 80 K and 110 K with onsets near 115 K as determined from resistivity.     

Contribution to the determination of the sensitivity of an ionization transducer

An analytic expression for the coefficient of secondary-electron collection has been obtained for an ionization transducer operating at pressures of 0.5–3 MPa. The coefficient is shown to be limited in the given case by the space charge of the beam being measured. A probability relation has been constructed for the ionization of air by electrons of various energies under normal conditions. A method is described for the calibration of the ionization transducer. The probability of the ionization of the residual gas at the pressures indicated has been determined experimentally.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 18–21, March, 1985.     

Eigenvalue Spectrum of a Dirac Particle in Static and Spherical Complex Potential

It has been observed that a quantum theory need not be Hermitian to have a real spectrum. We study the non-Hermitian relativistic quantum theories for many complex potentials, and obtain the real relativistic energy eigenvalues and corresponding eigenfunctions of a Dirac-charged particle in complex statically and spherically symmetric potentials. Complex Dirac–Eckart, complex Dirac–Rosen–Morse II, complex Dirac–Scarf and complex Dirac–Poschl–Teller potential are investigated.     

A study of the infrared spectra of carbon monoxide adsorbed on metals of the copper subgroup and on cobalt,ruthenium, rhodium,and palladium

A study has been made of the infrared spectra of carbon monoxide CO, adsorbed on Cu, Ag, Au, Co, Ru, Rh and Pd at temperatures from –160° C to 200° C and pressures from 10^–5 to 1–10 mm Hg. The spectra of CO adsorbed on Cu, Ag, and Au show one absorption band, characteristic of a surface compound of carbon monoxide, with linear structure. It has been found that in the stable chemosorption of CO on Co, Ru, Rh, and Pd in the range of temperatures and pressures studied, two types of surface compound-linear and bridged-are produced.     

Fourier transform emission spectroscopy of the TiF radical in the 407 nm region

Ultraviolet emission spectra of the TiF radical in the 407 nm region have been observed at a resolution of 0.04 cm⁻¹ using a Fourier transform spectrometer. A new electronic assignment of ⁴Γ–X⁴Φ has been proposed. Rotational analysis has been obtained for the 0–0 and 1–1 vibrational bands of the ⁴Γ_5/2–X⁴Φ_3/2, ⁴Γ_9/2–X⁴Φ_7/2, and ⁴Γ_11/2–X⁴Φ_9/2 subbands and the 0–0 band of ⁴Γ_7/2–X⁴Φ_5/2. The lower state rotational and centrifugal distortion constants are consistent with the previous results [J. Mol. Spectrosc. 184 (1997) 186; J. Chem. Phys. 119 (2003) 9496], to the conformation that the lower state of the 407 nm band is the ⁴Φ ground electronic state. Rough estimates of the vibrational interval ΔG(1/2) and the spin–orbit coupling constant A in the ⁴Γ state were also obtained.     

Calculation and study of the infrared absorption spectrum of 2, 5-dimethyl-4-phenylpyridine

The infrared absorption spectrum of 2, 5-dimethyl-4-phenylpyridine has been recorded in the range 400–2000 cm^–1 and the valence-force scheme has been used to calculate the values of the fundamental frequencies and the forms of the normal vibrations.In conclusion the author thanks M. M. Kusakov for directing the work and L. A. Gribov for discussion of the results.     

Vibrational spectroscopy and the intermolecular dynamics of condensed states VI. Temperature dependence of the intermolecular spectra for toluene,quinoline, and PCl3

The spectra have been examined for the polycrystalline and liquid states; the temperature ranges for orientation melting have been measured, as has the temperature range for the polymorphic transition in toluene. It is found that orientation ordering occurs in liquid quinoline near the usual melting point, and a short-range order structure is assumed. The behavior of toluene shows marked thermal hysteresis in the range from –50 to –150 ° C.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 69–72, February, 1972.     

Screening of an Electric Field and the Quasi-Static Capacitance of an Induced Charge in Semiconductors with Hopping Conductivity

Expressions for the screening length of an external electrostatic field in a crystalline semiconductor are derived in the Debye–Hückel and Mott–Schottky approximations taking into account electron (hole) hopping via hydrogen-like donors (acceptors). The feasibility of determining the Debye–Hückel screening length from measurements of a quasi-static capacitance with low and high degrees of basic dopant compensation has been demonstrated even in a strong field, that is, in the Mott–Schottky approximation. To measure the capacitance, the electric signal frequency must be much less than the average frequency of electron hopping via donors.     

Suppression of stimulated hyer-Raman scattering in lithium vapor

The stimulated hyper-Raman scattering (SHRS) in lithium vapor has been observed in both the forward and the backward directions as the laser was tuned near the 2S–3S and 2S–4S two-photon resonances. It is found that in the forward direction the SHRS associated with the 2P excitation near the 2S–3S or the 2S–4S two-photon resonance is completely suppressed, but the SHRS associated with the 3P excitation near the 2S–4S two-photon resonance can be observed. A condition under which the forward SHRS takes place, given by Malakyan [3], has been examined. A reasonable agreement between the theory and the experiment is obtained. Near the 2S–3S two-photon resonance, instead of the expected emission _2P–2S corresponding to the 2P–2S transition, an emission at the 2_P–_3S–2P frequency, which is close to the _2P–2S, has been observed in the backward direction. The process generating this emission could be considered as an inverse SHRS process induced by the 3S–2P spontaneous emission. For the SHRS emission a shift of the observed frequency from the calculated frequency has been found. In order to explain the shift, the Stark effect has been calculated. The results show that the shift can not be attributed to the Stark effect.     

Calculations of the Pressure of Polymorphic Transformation in Small Alkali-Halide Crystals

The present paper analyzes the properties of structural phase transitions under the extremal conditions of high pressures. In the context of the theory of density functional (TDF), the pressures of the B1–B2 transitions are calculated for small alkali-halide crystals as functions of the crystal size. The size effect of the B1–B2 transition – an increase in the transition pressure with the decreasing crystal grain radius – has been established for all investigated halides except lithium fluoride for which the dependence is reverse.