Vol. 35, No. 12 (1986)
1986, 35 (12): 1547-1555. doi: 10.7498/aps.35.1547
In a long and narrow trough parametrically excited by two frequency modes along vertical direction, the irrotational movement of an incompressible inviscid fluid has been investigated. Using the methods of multi-scale and average variational principle a nonlinear partial differential equations have been derived, that the complex displacement of the movement of fluid surface must satisfy. Under certain conditions, the solution of that equation can be obtained, it's a solitary wave with the waveform as hyperbolic secant function. Correspondingly the relations between the water parameters and the exciting variables have been discussed.
The operation of diffraction-limited misfocused correlator is analysed in terms of a model of off-axis optical Fourier-transformation system and the theory of Fresnel diffraction. It is proven that correlation still remains but between the intensity transmittance of the first transparency and the intensity diffraction pattern, of the second. The diffraction correlator can be modified as an interferometer, a general theory is deduced for it. The interferometry using two Ronchi gratings is discussed in detail, that yields lateral shearing interferogram, some corresponding experiment results are also given.It can be seen that the diffraction correlator is the setup of Lau effect for any plane objects and for any observating distance. Thus its application for interferometry is just as the interferometer directly based on the Lau effect.
1986, 35 (12): 1567-1573. doi: 10.7498/aps.35.1567
The damage profile of ion implanted silicon can be calculated from the spectroscopic elli-psometric data as well as the optical constants of crystalline and ion implanted amorphous state of silicon by means of optimization with a multilayer model. We measured the ellipsometric spectra and optical constants of ion implanted samples in the spectral range from 2.1 to 4.6 eV In the sense of optical characteristics, the degree of damage is defined using complex refractive index. We performed the calculation of damage profiles of 40 keV As+ implanted Si 〈111〉 at dosage of 4×1013 and 1.4×1014 ion cm-2, respectively, on the basis of simulated tests. The depth profiles of damage were obtained and compared with the experimental results of He+ back-scattering. The method of multilayer analysis can also be used to determine the profiles of other parameters of interest from optical spectra as long as the parameters markedly influence the optical response and do not depend upon the photon energy.
1986, 35 (12): 1574-1581. doi: 10.7498/aps.35.1574
The radiative transition and nonradiative process have been studied for Ho3+ ions in ZnS semiconductor. From the integrated emission intensity and excited state lifetime, the intensity uarameters of ZnS:Ho3+ were obtained and radiation probabilities and lifetimes of Ho3+ ion's nine energy levels were calculated. Nonradiative process among 5G6,3K8,5F2,5F3 and 5S2 ( 5F4) was investigated by measuring the emission intensity and fluorescence lifetime at differenttemperatures. 5G6, 3K8, 5F2 and 5F3 are in thermal equilibrium and there are 5 phononsparticipating in the multiphonon relaxation between 5F3 and 5S2( 5F4).
1986, 35 (12): 1582-1591. doi: 10.7498/aps.35.1582
The electronic structures of the ground states of S0 Se0 and Te0 pairs in Si are invesgated using the Green's function method with a tight binding Hamiltonian. Three different opinions are discussed. (S0)2, (Se0)2 or (Te0)2 in Si will introduce a symmetrical A1g state and an anti-symmetrical A2u state in the gap, both are fully occupied, the observed state is the shallower A1g state. The theoretical reason why the symmetrical A1g, state is higher than the antisymmetrical A2u state is analysed. The measured g factor of (Se2)+ in Si and the experimental data of ESR spectra for (S2)+ and (Se2)+ in Si also support the conclusions of the present paper.
1986, 35 (12): 1592-1597. doi: 10.7498/aps.35.1592
The temperature dependence of the anisotropy constants K1, K2 and the anisotropy field HA. of R2Fe14B (R = Ce, Pr, Gd) have been measured in temperature range of 1.5 K to 300 K. And the contribution of Pr3+ ions to the magnetocrystalline anisotropy of Pr2Fe14B compound was calculated by the single ion theory. The result is semiquantitatively consistent with the experiment.
1986, 35 (12): 1598-1602. doi: 10.7498/aps.35.1598
The ferroelastic domain walls in NdP5O14 crystals have been studied by means of X-ray fopography. It has been found that the ferroelastic domain walls appear to be black or white contrast in X-ray fopograph in the range of μt=0.6—7. The feature of the diffraction contrast of the ferroelastic domain walls is summarized as follows: (C2 - C1 = )△C//g contrast of the ferroelastic domain wall is strong △C⊥g contrast of the ferroelastic domain wall is invisible △C·g > 0 contrast of the ferroelastic domain wall appears to be black △C·g < 0 contrast of the ferroelastic domain wall appears to be white The diffraction contrast of the ferroelastic domain wall has been explained qualitatively by Penning-Polder's theory. According to the feature of the diffraction contrast, the structural characteristics of the ferroelastic domain wall has been discussed.
EXPERIMENTAL INVESTIGATION OF STABILITY OF PLANAR CRYSTAL-MELT INTERFACE AND EVOLUTION OF CELLULAR INTERFACE DURING CZOCHRALSKI GROWTH OF LiNbO3 SINGLE CRYSTALS DOPED WITH YTTRIUM
1986, 35 (12): 1603-1608. doi: 10.7498/aps.35.1603
By using periodic rotational striations as a time marker, the initial instability of a planar interface and the development of the cellular interface have been studied in Czochralski growth system of anisotropic LiNbO3 crystals doped with yttrium. The critical condition for very birth of instability of planar interface has been obtained. And there are two kinds of initial perturbations to be observed, that is, sinusoidal perturbation and sinusoidal travelling wave perturbation. Experimental results revealed that the planar interface evolves from sinusoidal perturbation to facetted perturbation to coarse facetted perturbation, finally, to stable cellular interface. It has been found that the wave-length of stable cellular interface is different from that of initial perturbation and always integral times larger than that of initial one. There is also a difference to be found between critical velocity of the plane-to-cell transition and that of cell-to-plane transition for a same crystal grown from the same system. It may be implied that the facetted cell is more stable than the nonfacetted plane.
1986, 35 (12): 1609-1615. doi: 10.7498/aps.35.1609
The contrast of birefringence images of dislocation in synthetic quartz crystal have been calculated with anisotropic elasto-optical coeffficients. Using reflection polarizing microscopy to compensate the natural optical activity, along the optical axis, we obtained the images of edge dislocations and compared it with the calculation.
1986, 35 (12): 1616-1623. doi: 10.7498/aps.35.1616
Superconducting A and B phases in triplet bipolaron system have been treated by useing the selfconsistent broken-symmetry Hartree approximation. The B phase is always more stable than the A phase in the weak coupling case. But in the strong coupling case, owing to the fluctuation feedback effect, the free energy of the A phase can be lower than that of the B phase, or the A-B transition may occur, which is analogous to the superfluid of 3He. The thermody-namic critical field Hc of the stable phase of the system has also been calculated and compared with the upper critical fields of heavy-fermion superconductors, UBe13, UPt3 and URi2Si2. It has been found that Hc can qualitatively account for the abnormal temperature dependences of the upper critical fields of these superconductors.
RELAXATION PROCESSES OF CARRIERS IN AMORPHOUS SEMICONDUCTOR SUPERLATTICES WITH MODULATEDLY DISTRIBUTED RECOMBINATION CENTERS
1986, 35 (12): 1624-1633. doi: 10.7498/aps.35.1624
We propose a continuous-time-random-walk model for a medium with moduiatedly distributed recombination centers to describe dynamical recombination processes of carriers in amorphous semiconductor superlattices. The survival probabilities of carriers are obtained in cases of different types of time distribution functions. Analysis of the results yields informations on the influences of the periodic potential wells and of the modulated doping on the macroscopic transport properties in this kind of artificial materials.
We have systematically analysed the ground electronic structures of atomic ions up to the atomic number 95 by the Dirac-Slater relativistic self-consistent field approximation method. The different electronic configuration competitions of atomic ions are discussed and will become the foundation for further theoretical studies. Basing on the smooth variation and the quasi-addition properties of the occupied obital screening constants, we have established the atomic data base of the ground electronic structures of all the atomic ions.
1986, 35 (12): 1640-1645. doi: 10.7498/aps.35.1640
The segregation kinetics of sulfur on the Ni (100) surface has been investigated by means of AES during heat treatment of the sample between 650℃ and 800℃. The concentration of segregated sulfur is proportional to the square root of time in agreement with McLean's model. The temperature dependence of the diffusion coefficient D is D(cm2/s) = 5×10-3 exp(-44600/RT). The LEED experiment shows that the saturated sulfur layer has a c(2×2)-S structure at room temperature. Depth profile analysis shows an exponential decrease of (S/Ni) Auger peak height ratio with time during argon ion bombardment.
1986, 35 (12): 1646-1651. doi: 10.7498/aps.35.1646
The surface phenomena of Pb97.4Sn2.6 alloy under the Ar+ ion sputtering have been investigated using PHI-590 scanning Auger microprobe at room temperature. Theoretical analyses of experimental data showed that the ion-bombardment-enhanced diffusion occured with diffusion coefficient up to 10-15 cm2/s and the thickness of alter layer was about 260 ?. The possible explanation is given.
1986, 35 (12): 1652-1656. doi: 10.7498/aps.35.1652
A phase factor was introduced into the wave function properly, and the correlation of the dipoles was taken into account by a semiclassical approach. Thus a successful explanation of the observability of quantum beat is obtained for various circumstances. Particularly, it has been made clear that there should be no single atom beat for the lower state splited cases, which removes the difficulty of semiclassical theory in explaining quantum beat. Therefore it has been shown that the semiclassical theory can rise to the challenge from quantum electrody namics in explaining quantum beat.
1986, 35 (12): 1657-1661. doi: 10.7498/aps.35.1657
Injecting a high power microwave into the CT-6B tokamak plasma, we performed the experiments on the pre-ionization of the tokamak discharge at the fundamental and the second harmonic resonance of the electron cyclotron wave. The experiments verified that the microwave pre-ionization is very effective for the reduction of the loop voltage and the magnetic flux in the early stage and suppression of the production of runaway electrons in the quasi-steady stage. The effect of the microwave pre-ionization with the fundamental cyclotron resonance is better than that with the second one.
1986, 35 (12): 1662-1666. doi: 10.7498/aps.35.1662
In this paper, we give the relation of double cohomology series constructed by de Rham cohomology and by horizontal or vertical variations in connection space. The relation with family index theorem is also shown.