Vol. 38, No. 5 (1989)
1989-03-05
CONTENT
1989, 38 (5): 699-705.
doi: 10.7498/aps.38.699
Abstract +
The effect of nonlinear gain and waveguide structure on the modal linewidth broadening produced by with quantum phase noise in semiconductor lasers is inverstigated with semiclassical theory. It is shown that the modal linewidth depends not only on the linear gain but also on the third order nonlinear gain and the waveguide structure. Thus a new linewidth broadening enhancement factor and a new mechanism of the power-independent linewidth component are proposed.
1989, 38 (5): 706-713.
doi: 10.7498/aps.38.706
Abstract +
This paper presents detailed studies on the bistability exhibited by the Langmuir-wave driven by a two-frequency laser. The equations governing the evolution of the amplitude and phase of the Langmuir-wave are derived fully relativistically. The bistable responses of both the saturated amplitude and steady amplitude of the Langmuirwave with respect to plasma frequency and pump intensity are studied, and the applications of hysteresis to laser-plasma Beat-Wave Accelerator are discussed. Finally the properties of the time evolution of the Langmuir-wave amplitude near the critical poim of the bistability are also investigated.
1989, 38 (5): 714-721.
doi: 10.7498/aps.38.714
Abstract +
A currentless plasma has been obtained in a tokamak device using a powerful microwave at electron cyclotron frequency generated by gyrotron systems. Its electron density is up to 8×1012cm-3; the electron temperature is up to 50 eV; the particle confinement time is about. 0.5ms; the heating efficiency is above 25%. The effect of the plasma on the toroidal breakdown and the heating mechanism have been studied.
1989, 38 (5): 722-727.
doi: 10.7498/aps.38.722
Abstract +
Interactions ot CO with the sodium-precovered Ag(110) have been studied with X-ray photoelcctron spectroscopy (XPS) and ultravilet photoelectron spectroscopy(UPS). It is shown that there are two weakly chemisorbed molecular states on the Na/Ag(110) at low temperature. As the annealing temperature increasing, only one state regains which is associated with the existence of Na. The further experimental evidences show that this state is a necessary precursor to the dissociated state.
1989, 38 (5): 728-734.
doi: 10.7498/aps.38.728
Abstract +
Backscattering spectrometry is used to systematically investigate the temperature, dose and dose-rate dependences of Mo/Si atomic mixing and reaction induced by 170 keV Ar+ ions and 300 keV Xe2+ ions. These results show that the ion beam mixing mechanism of Mo/Si system is not vacancy diffusion and intra-cascade interstitial diffusion, and the thermal spike model also does not apply. We suggest that thhe mechanism of Mo/Si atomic mixing induced by ion implantation should be interstitial diffusion and give a reaction model. Based on this concept, the experimental results can be explained.
1989, 38 (5): 735-744.
doi: 10.7498/aps.38.735
Abstract +
We derive a set of equations characterizing the quantum statistical properties of Jaynes-Cummings model, which may be used to describe overall the dynamical and statistical aspects in the interaction between a two-level atom and a single mode of the radiation field. Both interactions of a two-level atom with a vacuum field and a excited atom with a coherent field, as examples, are discussed in detail. Finally, the practicality of the above-mentionedi theoretical studies is demonstrated.
1989, 38 (5): 745-752.
doi: 10.7498/aps.38.745
Abstract +
Soliton and Raman self-pumped light propagation equations with the terms of cross nonlinearity are solved numerically by using the method of slit-step fourier transformation. Some general conclusions about Raman self-pumped light generation and its influence on soliton propagation are oftained. These conclusions are of important significance in soliton communication.
1989, 38 (5): 753-760.
doi: 10.7498/aps.38.753
Abstract +
According to a diagonal metric tensor, a set of exact gravitational soliton solutions of Einstein's equations in vacuum is obtained, which discribe two solitons propagating with constant velocity in opposite directions. After collision, they will continue to propagate without changing their original shape. Firally, the singularity and energy density of these solutions are also discussed.
FAR-INFRARED REFLECTION SPECTRA OF THE HIGH-Tc OXIDE SUPERCONDUCTORS MBa2Cu3O7-δ (M = Y, Sm, Gd, Eu)
1989, 38 (5): 761-767.
doi: 10.7498/aps.38.761
Abstract +
The farinfrared reflection spectra of the oxide superconductors MBa2Cu3O7-δ (M = Y, Sm, Gd, Eu) are reported in this paper. The spectra cover the frequency region of 40-360 cm-1, and the temperature varies from 4.2 K to 300 K. All the spectra of this series of oxide superconductors exhibit the same kind of structure: there are five reflection peaks and three inversion structures. The first two peaks at lower frequencies are identified to be associated with the collective vibrations of Ba, Cu, O ions and M, O ions, with B1a symmetry; other three peaks result from the bending vibrations of the Cu-O bonds. The three inversion structures in the spectra may be correlated to the superconducting energy gaps.
1989, 38 (5): 768-775.
doi: 10.7498/aps.38.768
Abstract +
The influence of low temperature proton irradiation on the transport property of high Tc oxide Y-Ba-Cu-O and La-Sr-Cu-O is studied by a standard four probe method. After irradiation, besides the resistivity of the sample increases and the superconducting transition temperature Tc decreases, the dp/dT of the sample increases and a metal-nonmetal phase trasition occurs. A strong annealing effect is found during warming up irradiated samples to room temperature. After room temperature annealing, nearly 60% of changes of the sample resistance and Tc which were caused by low temperature proton irradiation can be recovered. These phenomena can be attributed to that the electronic band structure of the high Tc oxide superconductor is very sensitive to the random defects.
1989, 38 (5): 776-783.
doi: 10.7498/aps.38.776
Abstract +
With monte-carlo method, the primary and second X-ray fluorescence excited by proton in thick target were simulated, and the fluorescence enhancing factors were obtained.The various enhancing factors were calculated with different proton incident energies and angles, X-ray ejection angles, and elements and their weight percentage in samples. Besides, the results of PIXE basically agreed with standard composition of steel samples using the calculated enhancing factors.
1989, 38 (5): 784-793.
doi: 10.7498/aps.38.784
Abstract +
In this paper, by the computer simulation of the structure of amorphous alloy, the influence of the size ratio of M atoms to TM atoms on the structure of amorphous alloy TM100-xMx is studied with almost the same composition. For this purpose, the structures of amorphous alloy Fe80P20, Co81P19 and Fe80B20 are simulated, and the influence of the change of the atomic size ratio on the structures of amorphous alloy is analyzed based on the partial reduced distribution function, topologic short-range order, stabilization of structurc and the change of atomic size by the electron transfer etc.
1989, 38 (5): 794-799.
doi: 10.7498/aps.38.794
Abstract +
In order to examine the electronic structure of amorphous Fe80B20-xMx (M = P, C, Si, Ge), the hyperfine field and the isomer shift of these alloys are obtained and analyzed. The number of the electrons transferred from metalloid to the 3d band of Fe is estimated on the basis of the "rigid band-donor" model. It is shown that the 4s electrons of iron take part in the charge transfer process. A possible resolution of the contradiction between the variation of magnetic moment and the counter charge transfer to the "rigid band-donor" model is given.
1989, 38 (5): 800-806.
doi: 10.7498/aps.38.800
Abstract +
The electrical conductivity and electron electrical conductivity of mordenite has been measured. The electrical conductivity and the activation energy of mordenite containing different water and ion-exchanged forms of mordenite have also been measured. The results show an ionic conductivity: the specific conductivity of mm denite is 10-6 to 10-5(Ω·cm)-1 in natural environment. The electrical conductivity of mordenite shows the change of its structure.
1989, 38 (5): 807-811.
doi: 10.7498/aps.38.807
Abstract +
By using mean field theory, we discuss the influence of size effect on surface exponenu and scaling laws of a film. We indicate that a crossover phenomenon would appear.
1989, 38 (5): 812-817.
doi: 10.7498/aps.38.812
Abstract +
The corrected coefficients for high frequence modulating (HFM) imaging formulas in holographic system are given. The exact results of the diffractive angle and coordinate value for imaging point can be obtained if corrected coefficient is used in these formulas to correct. The checking of results proved that the error in diffractive angle can be kept within 0.4 percent. The formulas of x3ν and y3ν which can be also computed simply from corrected coefficient as μ≤1 are given.
1989, 38 (5): 818-823.
doi: 10.7498/aps.38.818
Abstract +
The control of the modal linewidth broadening enhancement factor by a laterally coupled-cavity waveguide has been analyzed. It is found that when the coupling is weak and the fluctuations of injected nonequilibrium carriers due to spontaneous radiative recombination in the two cavities are independent, the modal linewidth broadening enhancement factor may approach zero, thus making the linewidth decrease by about an order of magnitude or more. The near- and far-field distributions and the modal discrimination between inphase and out-of phase modes are discussed.
1989, 38 (5): 824-828.
doi: 10.7498/aps.38.824
Abstract +
An approximate result of first neighborhood is given in ref [5] . In consideration of the importance of strict treatment about this problem, a new formula is derived. According to the computational comparision between the two formulas, it can be concluded that the approximate method in ref [5] is very simple, convenitnt and reliable. It is also concluded by adding random errors to the magnitudes of normalized structure factors that Hauptman's conclusion, namely, the two-phase structure invariants are only dependent on chemical composition and independent of the structure factors, is still correct in the two-wavelength case. Considering this fact, we suggest a fast computational method of the two-wavelength struc-ture invariants which may be useful in practical macrostructure crystallography.
1989, 38 (5): 829-833.
doi: 10.7498/aps.38.829
Abstract +
We have calculated the electronic states and the total energies of a variety of tetrahedrally co-ordinated atomic clusters using the molecular orbital theory CNDO of quantum chemistry. All models in the calculations are based on the cluster Si46 with a single vacancy in the center. We find that for the cluster of Si46H60H4*, in which all dangling bonds are saturated with hydrogen, the donor or acceptor levels in the gap clearly appear when the phosphorus or the boron is introduced substitutionally into the cluster, whereas no clear impurity levels is found for that without hydrogenation. In addition, the increase in total energy resulting from introducing phosphorus (or boron) into the hydrogenated cluster Si46H60H4* is evidently more than that of the cluster without hydrogenation. Our results have been explain d theoretically by the "8-N" rule. The specific role of hydrogen in doping mechanism and some recent experiments are discussed for a-Si:H films.
1989, 38 (5): 834-839.
doi: 10.7498/aps.38.834
Abstract +
In this paper, the M?ssbauer spectra of amorphous Fe81-xNixSi3.5B13.5C2 (x = 5, 10, 15, 20, 25, 30, 35) alloys and crystalline Fe50Ni50 are studied at room temperature and under external magnetic field. The hyperfine interaction parameters and hyperfine field distribution curves were obtained with the fitting spectrum method. The results indicated that there are two magnetic states of iron atom and Inver-like characteristic in amorphous Fe-Ni-Met alloys. Anomalous phenomena at about 15 at % Ni in Fe-Ni-Met alloys was revealed. It was suggested chat the conditions of external magnetic field and low temperature have the similar effect on the ordering of magnet. In the sometime, the mechanism of hybridization of the Fe 3d hand with the metalloid valence orbitals and the electron tranfer between transition metals was used to explain the experimental results for the amorphous transition metals (TM)-metalloid (Met) alloys.
1989, 38 (5): 840-845.
doi: 10.7498/aps.38.840
Abstract +
In this paper, we present a model of 2-D RICKY spin glass with nm1/21m beins the magnetic impurity concertration and 1 the mean free path (this corresponds to a large concertration of nonmagnetic defects). The specific heat and the magnetic susceptibility at low and high temperatures are calculated. The percolation theory is applied to the transition region. The broad maximum of the specific heat and the "cusp" of the magnetic susceptibility are explained.
1989, 38 (5): 846-848.
doi: 10.7498/aps.38.846
Abstract +
Some phenomena of tungsten bronze crystals growth were observed carefully. The effects of electrolytic temperature, current and time on the growth of crystals were studied and the optimum conditions for crystal growth were found. KxWO3,NayWO3 and KxNayWO3 crystals were produced successfully by fused salt electrolysis.
1989, 38 (5): 849-852.
doi: 10.7498/aps.38.849
Abstract +
KxWO3,NayWO3 and KxNayWO3 crystals were prepared by fused salt electrolysis. The X-ray diffraction, Raman, Infra-red we may conclude and condutivity me. asurements were made. From our results that KxNayWO3 is formed by intercalating Na+ ions into the tetragonal KxWO3 crystal lattice. A mechanism of ionic conduction is suggested.
1989, 38 (5): 853-858.
doi: 10.7498/aps.38.853
Abstract +
The 1 hour isochronal annealing treatment has been made on amorphous alloy Zr87.7Si12.3. The changes of the superconducting critical parameters, Tc and H(C2) and their transition width have been measured for different annealing temperatures. The different change laws of metal-metal type amorphous alloys were observed. The experimental results-were discussed in connection with the toplogical short range order and the chemical short range order in the process of structural relaxation and the corresponding crystallization mechanism.
1989, 38 (5): 859-863.
doi: 10.7498/aps.38.859
Abstract +
The γ-Fe2O3 surface evapourated with Co has been studied by photoemission spectros-copy. The results show that at low coverage, Co is very active and combined with the oxygen in γ-Fe2O3, while Fe in γ-Fe2O3 was reduced; at the coverage of 0.2-0.8 monolayer, some kind of CoFe2O4-like oxide was formed on the surface; with further Co coverage increasing, the Fe in the bulk began to segregate to the surface and the second monolayer of Co began to form on the surface, which destroyed the condition favourable to the formation of the oxide. We can conclude from these results that the magnetism improvement of magnetic powder coated with one- or sub- monolayer Co may have strong relation to the presence of this CoFe2O4-like oxide.
1989, 38 (5): 864-868.
doi: 10.7498/aps.38.864
Abstract +
The photoelectron spectrum from autoionizing atoms in strong laser field is investigated on the basis of ref [12] . Peak-switching similar to the corresponding effect in strong field multiphoton ionization is found, implying that the second-order ionization processes and high-order photoelectron peaks play essential roles in strong laser-field induced autoionization-These results show that many of previous results need to be revised.
1989, 38 (5): 869-872.
doi: 10.7498/aps.38.869
Abstract +
Based on the distribution and the morphology of the dislocations and other defects as well as the structural feature, the relationship between the defects and the structure of the rubidium acid phthalate crystal is discussed. In addition, a brief account of the defect formation is also given.
