中国物理B

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PERTURBATION TO THE SYMMETRIES AND ADIABATIC INVARIANTS OF HOLONOMIC VARIABLE MASS SYSTEMS

陈向炜, 梅凤翔

2000 (10): 721-725. doi: 10.1088/1009-1963/9/10/001

摘要 ( 1119 )

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The perturbation problem of symmetries for the holonomic variable mass systems under small excitation is discussed. The concept of high-order adiabatic invariant is presented, and the form of adiabatic invariants and the conditions for their existence are given. Then the corresponding inverse problem is studied. Finally an example is presented to illustrate these results.

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NORMALLY ORDERED FORMS OF SHAPIRO-WAGNER PHASE OPERATORS AND THEIR APPLICATION

梁先庭

2000 (10): 726-730. doi: 10.1088/1009-1963/9/10/002

摘要 ( 1224 )

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Based on the quantum mechanical representation |ξ〉=exp[\dfrac12|ξ|+ξ a⁺₁+ξ^* a⁺₂-a⁺₁a⁺₂]|00〉constructed by Fan Hong-yi and with the help of the technique of integration within an ordered product of operators, we derive the normally ordered expressions of the Shapiro-Wagner (SW) phase operators. They are in terms of the Bessel functions. As their application we discuss the minimal uncertain relation regarding the two-mode phase and number-difference operators.

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GENERAL FORMULA AND RECURRENCE FORMULA FOR RADIAL MATRIX ELEMENTS OF N-DIMENSIONAL ISOTROPIC HARMONIC OSCILLATOR

陈昌远

2000 (10): 731-736. doi: 10.1088/1009-1963/9/10/003

摘要 ( 1429 )

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In this paper, the general formulas and the recurrence formulas for radial matrix elements of N-dimensional isotropic harmonic oscillator are obtained. The relevant results of 2- dimensional and 3- dimensional isotropic harmonic oscillators reported in the reference papers are contained in a more general equations derived in this paper as special cases.

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DYNAMIC SCALING OF GROWING SURFACES WITH GROWTH INHOMOGENEITIES OF SCREENED COULOMBIC FUNCTION

唐刚, 马本堃

2000 (10): 737-741. doi: 10.1088/1009-1963/9/10/004

摘要 ( 1156 )

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The dynamic scaling properties of growing surfaces with growth inhomogeneities are studied by applying a dynamic renormalization-group analysis to the generalized Kardar-Parisi-Zhang(hereafter abbreviated to KPZ) equation, which contains an additional term of growth inhomogeneities. In a practical crystal growth process, these growth inhomogeneities can be induced by surface impurities and defects and are modeled by a screened Coulomb function in this paper. Our results show that the existence of the growth inhomogeneities can significantly change the dynamic scaling properties of a growing surface and can lead to a rougher surface.

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CALCULATION OF THE RELATIVISTIC CORRECTION ENERGIES OF Ne-LIKE IONS WITH ORBITAL POLARIZATION CORRECTION

李向东, 谭明亮, 易有根, 盛勇, 蒋刚, 张志红, 朱正和, 赵永宽, 唐永健

2000 (10): 742-748. doi: 10.1088/1009-1963/9/10/005

摘要 ( 1167 )

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This paper reports the theoretical calculation of Breit, self-energy, and vacuum polarization corrections in the Ne-like system using multi-configuration Dirac-Fock method with the orbital polarization. The relations of these corrections with the atomic number and the orbital symmetries are shown and the calculated correction energies are compared with other calculated results. Our Breit correction energies are all smaller by 1eV as maximum than the other theoretical Breit correction energies and the differences reveal ystematical relation with atomic number. It is found that the configuration interactions have great effect on Breit corrections while the orbital polarization has much smaller effect on Breit corrections. The self-energy and vacuum polarization obtained by our calculation are much different from that in previous literatures for some transitions.

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L-SHELL IONIZATION MEASUREMENT OF TUNGSTEN BY ELECTRON IMPACT

彭秀峰, 何福庆, 龙先灌, 安竹, 罗正明

2000 (10): 749-752. doi: 10.1088/1009-1963/9/10/006

摘要 ( 1120 )

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L-shell partial production cross sections of L_α^-, L_β^-, L_γ^- rays by electron impact were measured by observing the counts of X-ray from impacted thin tungsten target. Total production cross sections and mean ionization cross sections were deduced from these measured results. The electron beam energy range was from 11 to 36 keV. Tungsten was sputtered onto a carbon backing to reduce bremsstrahlung of the backing. The effect of electrons reflected by the backing has been corrected. Comparison with two theoretical calculations has performed. The experimental results agree rather well with the theoretical predications.

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THE NONLINEAR SCHR?DINGER EQUATION AND THE CROSS-PHASE MODULATION IN ERBIUM-DOPED FIBER AMPLIFIERS

刘宁, 刘颂豪, 廖常俊, 郭旗, 徐文成

2000 (10): 753-756. doi: 10.1088/1009-1963/9/10/007

摘要 ( 1241 )

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The nonlinear Schr$\ddot{o}$dinger equation(NLSE) in erbium-doped fiber(EDF) was obtained. The cross-phase modulation (XPM) in the erbium-doped fiber amplifiers (EDFA) was studied based on this NLSE and the rate equations. A more generalized form of the propagation equation in EDFA was obtained which included the phase shifts the EDFA induced. An analytical expression was given to the XPM in the EDFA. It was found that the XPM in the EDFA dose not change very much with the wavelength except at the neighboring wavelengths (around 1531 nm) where the absorption and emission cross-sections of the erbium ions reach their maxima, and the XPMs have opposite signs on the two sides around 1531 nm. Furthermore, it was found that the XPM increases with the increase of the length of EDF.

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A STUDY OF HIGH POWER MICROWAVE AIR BREAKDOWN

刘国治, 刘静月, 黄文华, 周金山, 宋晓欣, 宁辉

2000 (10): 757-763. doi: 10.1088/1009-1963/9/10/008

摘要 ( 1711 )

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This paper presents the results of research on microwave breakdown in air, it includes the experimental study and the theoretical analysis. The experimental study has been done in a waveguide with a frequency of 9.37GHz, the peak power up to 200kW, pulse width from 0.3 to 2.0μs. The repetition rate of microwave source is from single pulse to 970 pulse per second. The process of the breakdown of repetition pulse has also been recorded for a burst of ten pulses. A theoretical model for breakdown threshold is presented also. The theoretical are in good agreement with the experimental ones.

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PERTURBATION METHOD SOLVING ELASTIC PROBLEMS OF ICOSAHEDRAL QUASICRYSTALS CONTAINING A CIRCULAR CRACK

彭彦泽, 范天佑

2000 (10): 764-766. doi: 10.1088/1009-1963/9/10/009

摘要 ( 1076 )

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Perturbation method for solving elastic three-dimensional (3D) problems for 3D icosahedral quasicrystals is proposed. Considering an infinite 3D icosahedral quasicrystal weakened by a circular crack, we obtain the uniformly valid asymptotic solutions up to O(R²) for the mode I loading, where R is the elastic constant of phonon-phason coupling.

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LOW TEMPERATURE OPTICAL PROPERTIES OF AMORPHOUS OXIDE NANOCLUSTERS IN POLYMETHYL METHACRYLATE MATRIX

V. V. Volkov, 王中林, 邹炳锁, 解思深

2000 (10): 767-773. doi: 10.1088/1009-1963/9/10/010

摘要 ( 1470 )

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We studied the temperature-dependent steady-state and time-resolved fluorescence properties of very small (1-2 nm) ZnO, CdO, and PbO amorphous nanoclusters prepared in AOT reverse micelles and imbedded in polymethyl methacrylate(PMMA) films. X-ray diffraction and electron diffraction and imaging indicate that these structures are amorphous. These amorphous oxide nanoclusters demonstrate similar structural, electronic, and optical properties. Properties of steady-state fluorescence spectra indicate the unique localization of electronic states due to the amorphous structure. ZnO and CdO show double-band fluorescence structure, which is due to the spin-orbital splitting, similar to Cu₂O. Time-resolved fluorescence studies of the nanoclusters in the polymer reveal two lifetime components, as found in solution. The slow component reflects relaxation processes from band-tail states while the fast component may be related to high-lying extended states. The temperature dependence of fast fluorescence component reveals the presence of exciton hopping between anharmonic wells at temperatures higher than 200K. We correlate the barrier height between two wells formed around local atoms with the inter-atomic distance and bond ionicity.

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AuPd CATALYTIC NANOPARTICLE SIZE EFFECT ON THE FORMATION OF AMORPHOUS SILICON NANOWIRES

刘祖琴, 孙连峰, 唐东升, 周维亚, 李玉宝, 邹小平, 王刚

2000 (10): 774-777. doi: 10.1088/1009-1963/9/10/011

摘要 ( 1204 )

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Amorphous silicon (a-Si) nanowires have been prepared on SiO₂/Si substrates by AuPd nanoparticles / silane reaction method. Field-emission scanning electron microscopy and transmission electron microscopy were used to characterize the samples. The typical a-Si nanowires we obtained are of a uniform diameter about 20 nm and length up to several micrometers. The growth mechanism of the nanowires seems to be the vapor-liquid-solid mechanism. The catalytic particle size effect on the formation of the nanowires and the cause of forming amorphous state Si nanowires are discussed.

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POROUS AMORPHOUS FLUOROPOLYMER FILMS WITH ULTRALOW DIELECTRIC CONSTANT

丁士进, 王鹏飞, 张卫, 王季陶, 李伟, 张冶文, 夏钟福

2000 (10): 778-782. doi: 10.1088/1009-1963/9/10/012

摘要 ( 1205 )

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With the development of ultralarge scale integrated circuit, new interlayer dielectrics with low dielectric constant for multilevel interconnections are required, instead of conventional SiO₂ films. For the sake of seeking perfect dielectrics, amorphous fluoropolymer (AF) thin film with a thickness of about 0.9μm has been prepared by spin-coating method, following the principle of phase separation. By capacitance-voltage (C-V) measurements the dielectric constant of the thin film is equal to 1.57 at 1 MHz, which is attributed to numerous pores contained in the film matrix. X-ray photoelectron spectroscopy (XPS) spectra show that after annealing, about 71% CF₃ groups in the AF film have decomposed into CF₂, CF, etc. This leads to the increase of CF₂ groups by three times and CF groups by 8% in the AF film. In a word, compared with the film without being annealed, about 25% carbon, 7% fluorine and 12% oxygen atoms will be lost after annealing at 400℃ for 30min.

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1.5μm LUMINESCENCE CHARACTERISTIC OF ERBIUM IN B, P DOPED a-SiO:H FILMS

梁建军, 陈维德, 王永谦, 常勇, 王占国

2000 (10): 783-786. doi: 10.1088/1009-1963/9/10/013

摘要 ( 1223 )

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Hydrogenated amorphous silicon films co-doped with oxygen (O), boron (B) and phosphorus (P) were fabricated using PECVD technique. The erbium (Er) implanted samples were annealed in a N₂ ambient by rapid thermal annealing. Strong photoluminescence (PL) spectra of these samples were observed at room temperature. The incorporation of O, B and P could not only enhance the PL intensity but also the thermal annealing temperature of the strongest PL intensity. It seems that the incorporation of B or P can decrease the grain boundary potential barriers thus leading to an easier movement of carriers and a stronger PL intensity. Temperature dependence of PL indicated the thermal quenching of Er-doped hydrogenated amorphous silicon is very weak.

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SPECTRAL VARIABILITY AND TRANSIENT INJECTION OF RELATIVISTIC ELECTRONS FOR BL LAC OBJECTS

梅冬成, 谢光中, 陈洛恩

2000 (10): 787-790. doi: 10.1088/1009-1963/9/10/014

摘要 ( 1251 )

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The spectral hardening with increasing intensity in optical range for four BL Lac objects have been found by analyzing our observed data. Making use of the synchrotron loss of transient injection of relativistic electrons, we succeeded in explaining the phenomenon of the spectral hardening in the outburst phase. The value of magnetic intensity and the limit condition of the transient injection of relativistic electrons seem to be reasonable.

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