On the kineteic theory of electron cyclotron maser

This paper starts from the kinetic theory to expound the method of characteristics. Influence of the equilibrium distribution functionf _o upon analyzed result is fully investigated. Dispersion equation is rigorously derived in waveguide coordinate system in case of interaction between TE _mn field in a circular waveguide and a single momentum ring-shaped electron beam. In the meantime, we make some critical review of previous papers and clarify their confusion and ambiguities.     

Radial drift invariant in long-thin mirrors

In omnigenous systems, guiding centers are constrained to move on magnetic surfaces. Since a magnetic surface is determined by a constant radial Clebsch coordinate, omnigeneity implies that the guiding center radial coordinate (the Clebsch coordinate) is a constant of motion. Near omnigeneity is probably a requirement for high quality confinement and in such systems only small oscillatory radial banana guiding center excursions from the average drift surface occur. The guiding center radial coordinate is then the leading term for a more precise radial drift invariant I _r , corrected by oscillatory “banana ripple” terms. An analytical expression for the radial invariant is derived for long-thin quadrupolar mirror equilibria. The formula for the invariant is then used in a Vlasov distribution function. Comparisons are first made with Vlasov equilibria using the adiabatic parallel invariant. To model radial density profiles, it is necessary to use the radial invariant (the parallel invariant is insufficient for this). The results are also compared with a fluid approach. In several aspects, the fluid and Vlasov system with the radial invariant give analogous predictions. One difference is that the parallel current associated with finite banana widths could be derived from the radial invariant.     

Quantum-chemical modeling of structural,electronic, and spin characteristics of NV centers in nanostructured diamond: Surface effect

The effect of the surface of diamond on atomic, electronic, and spin properties of diamond nanocrystals containing single nitrogen-vacancy defects ([NV]⁻ centers) is studied. The surface was modeled with clusters C₃₃H₃₀[NV]⁻, C₆₆H₇₂[NV]⁻, which were constructed based on bulk clusters C₃₃H₃₆[NV]⁻ and C₆₉H₈₄[NV]⁻, respectively. In all cases, clusters in the triplet state S = 1 are considered with the cluster charge being −1. The geometric structure of clusters is optimized using the principle of minimization of the total energy of the system; then, the electronic and spin characteristics of clusters are calculated by the density functional theory. The isotropic and anisotropic hyperfine interaction constants of the electron spin of the NV center with the nuclear spin of the nitrogen atom and ¹³C atoms located at different sites in the cluster are calculated. It is found that, in contrast to bulk clusters with [NV]-centers in which the spin density is mainly localized at the three carbon atoms that are the nearest neighbors of the vacancy of the center, upon arrangement of the NV center in the immediate proximity to the surface, the spin density is redistributed such that it is mainly localized at the three carbon atoms that are the nearest neighbors of the nitrogen atom of the center and at C atoms that form the first atomic layer of the (111) surface of the nanocrystal.     

Kinetic theory of a cyclotron-undulator hybrid fel in circular waveguide

In this paper, we model the cyclotron-undulator hydrid instability using the kinetic theory in circular waveguide geometry, following the generalized method of the field expansion in the guiding center coordinate system; and derive in detail the coupling coefficient for a cyclotron-undulator hybrid FEL operating at the fundamental harmonic of gyration and undulation. In our discussion, the effect of the transverse structure of the radiation fields is taken into account, but the undulator is considered as an ideally longitudinal one.     

Vibrational Spectra and Normal Coordinate Analysis for an Imidazole Bridged Copper,Zinc Binuclear Complex

Abstract

The normal coordinate analysis of a model compound for Cu, Zn-SOD: [(dtma)CuImZn(dtma)]CIO₄ · 2.5H₂O (where dtma = 4-diethylenetriamineacctate; Im = imidazolate) has been carried out by using a Urey-Bradley force field. According to the molecular structure, 240 internal coordinates were established and 174 theoretical vibrational frequencies were calculated. Due to introducing an appropriate set of internal coordinates and force constants in the course of calculation, the calculated frequencies agree well with the observed values, with the average difference 4.40cm^?1 and the maximum deviation 24.2cm^?1 between them, although the structure of the title compound is complicated. Some structural and spectral properties are here discussed.     

横向Zeeman He—Ne激光器中非线性混频效应的理论

本文在文献[1]的基础上,考虑了原子速度的Maxwell分布,利用矢量场模型和Lamb半经典理论,研究了横向Zeeman He-Ne激光器中近简并四波混频效应,给出了高阶非线性项的计算公式,从理论上解释了拍频曲线畸变的物理原因。并利用计算机进行了数值求解,结果表明本文的理论预言与实验结果相符。 关键词：     

标量-张量引力波

本文的结果大部分已在文献[1]中发表,这里给以完整的证明.此外,还证明了D型的标量-张量波不存在。     

Statistical theory of angular momentum polarization in chemical reactions

A general statistical treatment applicable to any vector property of reactive scattering is derived from angular correlation theory. This pertains to the usual experimental situation in which two or three vector directions are observed but numerous other vectors are random or unobserved, particularly various angular momentum vectors. The dependence of the cross section on the angles relating the observed vectors is expanded as a Legendre polynomial series, with coefficients which represent averages of angular momentum functions over the unobserved vectors. An algorithm for calculating these angular correlation coefficients is provided by the statistical theory. All non-vanishing terms involve only even-order Legendre polynomials. In many experiments, one or two terms are predominant. Classical and quantal versions give the same algorithm in the correspondence principle limit, which often holds for chemical reactions. The angular correlations involving the initial and final relative velocity vector directions [kcirc] and [kcirc]′ and the product rotational angular momentum j′ are treated in detail, including both pairwise and triple correlations. Explicit formulae are given for three choices of the quantization axis : along [kcirc], along [kcirc]′, and along [kcirc] × [kcirc]′. Coefficients for the ([kcirc], [kcirc]′, j′) correlations are tabulated for seven reactions as examples and comparison made with recent experimental measurements of the spatial orientation or polarization of j′ in reactions of alkali atoms with hydrogen halides and with methyl iodide.     

Waveguide CO2 lasers on sequence-band transitions

Two waveguide CO₂ lasers, a quartz waveguide and an alumina waveguide, have been studied on the 00°2–[10°l,02°1]_I,II sequence bands. The use of an intra-cavity hot CO₂ cell, which is a part of the waveguide, suppresses the regular-band transitions. The quartz waveguide laser has a total of 58 lines lasing on both the 9.4 µm and 10.4 µ,m sequence bands. The alumina waveguide laser has 36 lines lasing on the 10.4 µm sequence band and twice the output power of the quartz waveguide laser, whereas lasing on the 9.4 µm sequence band is difficult. The lasers can be operated on the selected single line without line jumping problem. The frequency tuning range of the strong lines is limited by the free spectral range of the cavity.     

Statistical theory of angular momentum polarization in chemical reactions

A general statistical treatment applicable to any vector property of reactive scattering is derived from angular correlation theory. This pertains to the usual experimental situation in which two or three vector directions are observed but numerous other vectors are random or unobserved, particularly various angular momentum vectors. The dependence of the cross section on the angles relating the observed vectors is expanded as a Legendre polynomial series, with coefficients which represent averages of angular momentum functions over the unobserved vectors. An algorithm for calculating these angular correlation coefficients is provided by the statistical theory. All non-vanishing terms involve only even-order Legendre polynomials. In many experiments, one or two terms are predominant. Classical and quantal versions give the same algorithm in the correspondence principle limit, which often holds for chemical reactions. The angular correlations involving the initial and final relative velocity vector directions [kcirc] and [kcirc]′ and the product rotational angular momentum j′ are treated in detail, including both pairwise and triple correlations. Explicit formulae are given for three choices of the quantization axis: along [kcirc], along [kcirc]′, and along [kcirc] × [kcirc]′. Coefficients for the ([kcirc], [kcirc]′, j′) correlations are tabulated for seven reactions as examples and comparison made with recent experimental measurements of the spatial orientation or polarization of j′ in reactions of alkali atoms with hydrogen halides and with methyl iodide.     

γ辐射对光纤波导电磁场分布的影响

开展了光纤波导中的电磁场传输理论分析,得到了光纤折射率变化对波导中电磁场分布的影响规律,建立了块状融石英材料及光纤光栅在60Co 辐射作用下折射率变化的测量系统,开展了折射率随辐射剂量变化及光纤模场测量实验。结果表明:光纤的折射率随辐射剂量的增加而增大,折射率的变化会引起波导中传输模式的场强分布变化,从而导致光纤的辐射感生波导损耗;在一定的辐射剂量范围（0～2000 Gy）内,光纤仍满足弱导边界条件,能够维持对传输模式的约束能力。     

Normal Coordinate Analysis of 3-Bromo-1,3-Dinitroazetidine

Abstract

The infrared spectrum of 3-bromo-1,3-dinitroazetidine was interpreted with the aid of normal coordinate calculations. A seventy-two parameter modified valence field was used in those calculations, and the observed wave numbers were fit with an average error of 2.5 cm^?1. An assignment of the bands in terms of symmetry coordinates is given. Many of the force constants were transferred to 1-acetyl-3,3-dinitroazetidine to aid in normal coordinate calculations for that compound.     

Monazite (monoclinic LaPO4) slip systems at room temperature

Polycrystalline monazite (monoclinic LaPO₄) was deformed by spherical indentation at room temperature. Slip systems were identified using TEM of thin sections prepared parallel and close to the indented surface. Dislocation Burgers vectors (b) were identified by Burgers circuit closure in high resolution TEM images, supplemented by diffraction contrast where possible. A total of 441 b determinations were made in 97 grains. The most common slip systems were [001]/(010), [100]/(010) and [010]/(100). Slip on (001) was less common. Many other less common slip systems and Burgers vectors were also identified, including b = [101], [101], [011], [110] and [111]. b = [101] dislocations dissociate into ½[101] partials, and b = [101] dislocations are inferred to dissociate to ½[101] partials, with a low energy stacking fault of ～30 mJ/m². b = [100] dislocations may dissociate into ¼[210] + ¼[210] partials. b = [010] may sometimes dissociate to ½[010] + ½[010] partials. Other types of partial dislocations were also observed and discussed. All partial dislocations were climb dissociated. The line energies of monazite dislocations and their partials were calculated, and stacking fault structures for partial dislocations are analyzed. Satisfaction of the Von Mises criterion for full ductility most likely involves [101]/(111) and ?011?/{011} or {111} slip, but other combinations that require both b = [101] and ?011? or ?110? are possible. If deformation twinning is active, slip systems with b = ?011? or ?110? may not be necessary for full ductility.     

Molecular Force Field of Methanol

Abstract

Normal coordinate analysis was carried out on the vapor phase Raman and i.r. spectral data of methanol and its deuterated species to determine a vibrational force field. Based on the results of calculations, the 25-parameter molecular force field was analyzed and compared with the earlier studies and the vibrational band assignments were discussed in terms of the vibrational mode mixings, particularly, in the wavenumber region below 1500 cm^?1.     

A new quasi-Ising magnet

We have performed measurements of the magnetization and differential magnetic susceptibility of Dy_0.62Y_2.38Fe₅O₁₂ single crystals in pulsed magnetic fields up to 45 T at liquid-helium temperature for three orientations of the external field: H‖[100], H‖[110], and H‖[111]. It was found that the magnetization reversal in the rare-earth magnetic subsystem occurs via several phase transitions, whose number depends on the direction of the external field, as is characteristic for Ising magnets. The anomalies in the field dependences of the magnetization are interpreted on the assumption of quasi-Ising ordering of the rare-earth ions. Pis’ma Zh. éksp. Teor. Fiz. 67, No. 8, 552–556 (25 April 1998)     

THE QCD BEHAVIOUR FOR THE VALENCE QUARK DISTRIBUTION FUNCTION OF PION IN THE LEADING LOGARITHM APPROXIMATION AND RELEVANT DIFFERENTIAL CROSS-SECTION

Using the analytic expression for valence quark distribution function of hadron in the leading logarithm approximation given by paper^[11], we discuss the QCD behaviour for the valence quark distribution function of pion. The existing data for valence quark distribution function of pion are explained excellently. We also predict the differential cross section M³ dσ/dM for massive lepton pairr production with Drell-Yan mechanism and compare it with data.     

Vibrational Analysis of 1,2-Dibromopropane and 1,2-Dibromopropane-D6

Abstract

Infrared spectra were obtained for 1,2-dibromopropane-d₆ in the liquid and in the unannealed and annealed solid states. Vibrational assignments were made for the three conformers of 1,2-dibromopropane and the three conformers of 1,2-dibromopropane-d₆ with the aid of normal coordinate calculations. All three possible conformers of CD₂BrCDBrCD₃ were found to be present in the liquid and unannealed solid, but the P_HS_HH conformer was absent in the annealed solid.     

Thermoelastic behaviour of hexagonal graphite-like boron nitride

Abstract

A synchrotron X-ray diffraction study on hexagonal graphite-like boron nitride (h-BN) was performed under high pressures and temperatures. From the measured P-V-Trelation for h-BN (with a three-dimensional ordering parameter P₃ = 0.9) in the temperature range from 298 to 1273 K and up to 6.7 GPa, the thermoelastic parameters are derived by fitting a modified high temperature Birch-Murnaghan equation of state. The results are: bulk modulus B₀[GPa] = 27.6-0.0081(T[K]-298) and its pressure derivative B¹ = 10.5 + 0.0016(T [K] - 298). These values are for samples with P₃ = 0.9 and are quite different for samples with different values of the order parameter. This parameter is shown to have a leading role in the determination of the thermoelastic properties of h-BN, which explains and reconciles the differences between previous results.     

Homothetic motions in general relativity

Properties of homothetic or self-similar motions in general relativity are examined with particular reference to vacuum and perfect-fluid space-times. The role of the homothetic bivector with componentsH _[a;b] formed from the homothetic vectorH is discussed in some detail. It is proved that a vacuum space-time only admits a nontrivial homothetic motion if the homothetic vector field is non-null and is not hypersurface orthogonal. As a subcase of a more general result it is shown that a perfect-fluid space-time cannot admit a nontrivial homothetic vector which is orthogonal to the fluid velocity 4-vector.