Hawking thermal spectrum of a spherically charged evaporating black hole can be obtained by means of the second quantization and Bogolubov transformation on Klein-Gordon scalar field near the event horizon of Vaidya-Bonner space-time. It is shown that the ingoing vacuum state becomes an outgoing state involving thermal particles after scattering on the surface of horizon. These particles show Planck spectrum whose temperature is T.

We have studied the properties of the amplitude-N-th powered squeezing of an elec-tromagnetic field in the k-photon Jaynes-Cummings model of an atom initially being in the ground state and coupling with the superposition state. The results show that, under the condition of n≥k, where n is the photon number of the superposition state, the field exhibits not only the amplitude-N = n-th powered squeezing but also the amplitude-N = (n/2)-th powered squeezing for even n. The variations of the amplitude-N-th powered squeezing of the field with the powers N and k are discussed.

There are two dynamical stable zones in the operation of solid laser containing a thermal lens. In this paper, we point out that in the two stable zones two kinds of dynamical stable states can exist in a laser resonator: mode-steady thermo-stable state and power-steady thermo-stable state. They are different from each other in general. The operating conditions for power-steady thermo-stable state are presented. A cw Nd: YAG thermo-stable resonator operating in power-steady states has been designed, and 40 W TEM_{00} output power in 1.06μm is obtained experimentally.

CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES

By utilizing the powder X-ray step-scanning diffraction data of PbSO_{4}, we have studied the effect of the diffraction data (with different high-angle upper-limit: 2θ_{m}= 160,140,120,100,80, 70 and 60°) on the precision of the Rietveld refined lattice constants, structure parameters, and agreement indices. Tbese refined results are compared with those obtained from the single crystal data. It is revealed that the deviations of the refined lattice constants, atomic positions and isotropic temperature factors decrease, and agreement indices become smaller With the increase of 2θ_{m}. But when 2θ_{m}> 120°, the deviations and agreement indices decrease very slowly. Therefore, in general cases, 2θ_{m} should be taken to be 120°or larger in order to get satisfactory refined results in the Rietveld crystal structure refinement.

The crystallization of the amorphous Cu_{60}Zr_{40} alloy has been studied by differential scanning calorimetry (DSC), scanning Auger microprobe (SAM) and transmission electron microscopy (TEM). The DSC trace showed that the sample exhibited a glass transition at 750 K and a strong exothermic effect beginning from 782 K. An enrichment of the element Zr and significant oxygen contamination in a zone near the surface to a depth of about 10 nm were revealed by SAM in the analysis of surface competition and depth profiles of the Cu_{60}Zr_{40} sample. Also, the change of concentration ratio of Ca to Zr in amorphous matrix at the clean Cu_{60}Zr_{40} surface as a function of annealing temperature was examined in detail, and it was found that the concentration of Zr at the surface is slightly higher than that in the bulk until 780K and that the concentration ratio of Cu to Zr in matrix has an abrupt increase in the temperature range of 780-800K. The observations by high resolution TEM revealed the appearance of cluster-like regions of approximately 1.5-2.0 nm in size just before crystallization and they distributed randomly throughout the sample. This phenomenon is analogous to the results obtained using field ion microscopy (FIM) by the present authors. The microstructural changes of the sample daring heating show the gradual crystallization of the amorphous matrix.

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES

In this paper, the extended Wannier function suitable for instable lattice is constructed, by employing a linear combination of hydrogenlike-atom wave functions, and used to calculate the non-nearest-neighbor hopping and energy-band structure of trans-polyacetylene. Studies show that the non-nearest-neighbor terms have a considerable influence on the band structure. The computed results agree very well with the experimental results.

Based on a theoretical model proposed for quasi-one-dimensional organic polymer ferro-magnet poly-BIPO, the effects of electron-electron interaction and electron-phonon coupling on the spin-density-wave (SDW) state of poly-BIPO system are studied. It is found that the SDW state is the stable ground state of the system, in which the system shows ferromagnetic order. And the larger electron-electron interaction and the smaller electron-phonon coupling will make the SDW state more stable than the nonmagnetic state.

The influence of irradiation by 30 keV nitrogen ions with a fluence 1×10^{18}N^{+}·cm^{-2} on the crystal structure of single crystal Bi_{2}Sr_{2}CaCu_{2}O_{7-y} was investigated by means of X-ray photoelectron spectroscopy and X-ray diffraction. The irradiation caused a transformation from Bi_{2}Sr_{2}CaCu_{2}O_{7-y} (2212 phase) to Bi_{2}Sr_{2}CuO_{5-x} (2201 phase). It was observed that. a small amount of metallic bismuth with an average thickness of about 6.3nm appeared after the irradiation. The possible reaction mechanism under nitrogen-ion irradiation was discussed.

Low-temperature scanning electron microscopy (LTSEM) is a promising measuring technique for probing the spatial distribution of the superconducting properties of the high-temperature superconducting (HTS) thin films. A theoretical analysis of the electron-beam irradiation on the HTS thin films in the LTSEM has been carried out. An inhomogeneously distributed grain array model has been applied in the analysis, and some numerical sim-ulations have been carried out on the electron-beam induced voltage (EIV) signals in the LTSEM experiments. The comparisons of our numerical results with the LTSEM experi-mental data indicate that it is quite reasonable to use a two-dimensional Josephson junction array for stimulating the inhomogeneous HTS thin film sample. Our numerical results also show that the EIV signals are influenced by the electron-beam power used in the LTSEM, and a reduction of the electron-beam power is suggested in order to eliminate the errors in estimating the local values of critical temperature T_{c} and critical current I_{c} by the sample temperature and the bias current at which the first EIV signal occurs.

[an error occurred while processing this directive]