Vol. 38, No. 9 (1989)
1989-05-05
CONTENT
1989, 38 (9): 1391-1399.
doi: 10.7498/aps.38.1391
Abstract +
In this paper two kinds of photocapacitance transientes, corresponding respectively to two cases of coupling and uncoupling of two or more deep levels have been studied in detail. According to the great difference of the two kinds of the photocapacitance transientes, a method of determining if two or more deep levels belong to the same center has been suggested. It has some advantages that it can be used to measure the sample including more than two deep levels, the processes are quite simple, and it takes short time to finish a measurement. For example, this method has been used to judge the donor and acceptor levels related to gold in Si. The result has proved that they belong to the same center related to gold in Si.
1989, 38 (9): 1400-1405.
doi: 10.7498/aps.38.1400
Abstract +
The interactions between incident particles and solids in ion implantation have been in-vestigated based on the generalized Langevin equation of classical dynamics. Considering an-harmonic effects of interactions among lattice atoms the energy exchange between incident particles and target atoms, the nuclear stopping power and the distributions of project ranges have been calculated numerically. The effect of the phonon spectra excited by the incident particles has been discussed also. All calculations are in good agreement with the results of the program TRIM88 in the low energy range.
1989, 38 (9): 1406-1412.
doi: 10.7498/aps.38.1406
Abstract +
There is recent interest in atomic inner-shell two-photon decay processes because state-of-art experimental techniques (such as electronic coincident measurement etc.) have made it possible to measure the two-photon decay rate in the X-ray region. We perform relativistic self-consistent field calculations on the two-photon decay rates of (ls)-1→(ns)-1 transitions (n = 2,3,4) and (ls)-1→(nd)-1 transitions (n = 3,4) for hydrogen, hydrogen-like Xe ion and Xe atoms. Comparing the hydrogemc and the hydrogen-like Xe ion rates, we can clearly demonstrate the relativistic effect. Comparing our previous non-relativistic and our present relativistic Xe atom rates, we can also demonstrate the relativistic effect in the atomic inner-shell two photon decays. Comparing the hydrogen-like Xe ion and the Xe atom rates, we can explain the atomic screening effect. After elucidating the relativistic effect and the atomic screening effect, we are convinced that we have obtained the reliable relativistic rates, which can provide a basis to analyze th effect of electron correlations in the atomic inner-shell two-photon decays. We also compare our results with the experimental measurement and other theoretical results.
1989, 38 (9): 1413-1421.
doi: 10.7498/aps.38.1413
Abstract +
The selfconsistent semiclassical approach is extended from the case of zero temperature to finite temperature to determine the nucleon densities of hot nuclei. The properties of giant resonances on hot nuclei, espencially the temperature dependence of the centroids, are evaluated and analysed with help of the densities above determined. Some of the present results are compared with those of HF and RPA.
1989, 38 (9): 1422-1428.
doi: 10.7498/aps.38.1422
Abstract +
In the paper, we use the theory of order-disorder transition to discuss this kind of transition in A(B1/21 B1/22)O3 system. We point out thai interaction energy parameter J plays an important role in the formation of ordered domain with B:B = 1:1. In addition, the relation among the interaction, charge and size of the B-site ions is discussed. The results are in agreement with experiments reasonably.
1989, 38 (9): 1429-1435.
doi: 10.7498/aps.38.1429
Abstract +
The compounds YTi (Fe1-xNix)11 are found to crystallize in the ThMn12-type tetragonal structure (space group 14/mmm) when x1-xNix)11 has been studied and explained in terms of the interatomic distance dependence of exchange interaction between Fe atoms.
1989, 38 (9): 1436-1442.
doi: 10.7498/aps.38.1436
Abstract +
In this paper, a semiclassical rate equation model has been established and the FM noise power spectrum calculated. We show that the spectral line width can be narrowed by the negative electrical feedback technique. Within the feedback loop bandwidth, the chirp-power-ratio (CPR) is reduced by a factor of 1+H, it shows that this kind of laser can be used as the light source in FSK coherent transmission system. Because of the direct modulation phase delay of the semiconductor laser, l/f-type FM noise is one of the important origin of the limitation, for linewidth reduction.
1989, 38 (9): 1443-1453.
doi: 10.7498/aps.38.1443
Abstract +
The Point defect concentrations around voids and dislocations in irradiated materials were studied using reaction-diffusion equations. The equations which contained the terms involving recombination of vacancies and interstitials were solved approximately. It turned out that the effects of the recombination on the sink strengths cannot be neglected when damage dose rate and void size become large Actually, we obtain that when void radius is greater than 200A and damage dose rate reaches 10-2 dPa/s the values of void sink and dislocation sink streng ths exceed more than 50% of those given by previous works.
1989, 38 (9): 1454-1466.
doi: 10.7498/aps.38.1454
Abstract +
Approximate concentration distributions of point defects around a dislocation in irradiated material are obtained by dividing the region near the dislocation into two parts in which some definite approximations are used. Then dislocation biasfactor for interstitials is determined, the value of the factor is less than the previous one by 20-50%. As a result, a formula of swelling due to void growth in irradiated materials is obtained, it agrees with experimental data reasonably.
1989, 38 (9): 1467-1474.
doi: 10.7498/aps.38.1467
Abstract +
This paper provide the microscopic phenomenological theory of analysis for the problem of nonequilibrium fluctuations, i.e. the statistical theory for description of nonequilibrium fluctuations. This theory is based on a generalized nonequilibrium entropy and an extension of the Einstein formula for the probability of the fluctuations. We obtain the second moments of nonequilibrium fluctuation of the specific energy and the heat flux in rigid heat conductors by calculation. This approach leads to nonequilibrium corrections to the conventional fluctuation-dissipation expressions for the heat fluctuations. The corresponding numerical corrections are obtained for phonon heat transport in dielectrics and for electronic heat transport in metals.
1989, 38 (9): 1475-1482.
doi: 10.7498/aps.38.1475
Abstract +
Effective nearest- and next nearest-neighbor interactions are used to study phonons and phonon softening at Mo(00l) surface with continuously varying the surface interaction parameters αs, and βs. The phonon stability diagram is obtained. The vibrational modes and softening of surface waves are investigated. The relations between softening of surface waves and reconstruction of Mo(00l) surface are discussed in some detail.
1989, 38 (9): 1483-1491.
doi: 10.7498/aps.38.1483
Abstract +
We propose an ideal configuration of a dislocation obliquely intersecting the phase boundary in a two phase medium. By employing the general integral method of anisotropic elas-tic theory of dislocations and the Gibbia-Eshelby theorem for boundaries, we obtain the numerical solutions for elastic field of this dislocation as well as the "image" force acting on it. Our model and computing method are shown to be applicable in general. The results can be used to further calculate the interaction between this dialocation and other defects. This work is also a meaningful starting point for considering the effect of such oblique dislocations in diffusionless phase transformations.
1989, 38 (9): 1492-1496.
doi: 10.7498/aps.38.1492
Abstract +
When the dopping is low enough, the holes obey Bose statistics[14], Bose-Einstein condensation of these holes may lead to occurance of superconductivity. In this framework, we have calculated some physical quantities, the results are in qualitative agreement with experiments.
1989, 38 (9): 1497-1500.
doi: 10.7498/aps.38.1497
Abstract +
Based on the renormalization effect of the phonon ground state on the tunneling parameters, a new method is proposed to investigate the localization-dislocalization transition of a tunneling system with bosonic bath. Our study shows the previous theories are in principle built on the displaced phonon state approximation, while our method may be used to examine the effects of other type of phonon ground states (such as squeezed phonon state) on the localization-dislocalization transition.
1989, 38 (9): 1501-1505.
doi: 10.7498/aps.38.1501
Abstract +
We generalize the resuits of ref. [1] , expplain the proof of the formulae shown in this paper by the method of the inverse orbits analysis. According to this, we can calculate the value of the topological entropy on any point in the whole parameter interval. On the basis of discussing the effect of "*" product on the topological entropy, we obtain the overview of the topological entropy of one-dimensional maps.
1989, 38 (9): 1506-1509.
doi: 10.7498/aps.38.1506
Abstract +
We have proposed a simple Hamiltonian for poly(p-phenylene) in the framework of SSH tight binding model. The calculations presented to the ground state, polaron and bipolaron show that the formation of doubly charged bipolaron is energetically more favorable than the-formation of two polarons with single, charge. Because the period of the chain is 4a, the CB and VB band will split in two, and when there is a polaron (or bipolaron) in the chain, shallow energe levels will emerge near each band edge besides the polaron (or bipolaron) energe levels, all the corresponding electronic states are localized.
1989, 38 (9): 1510-1514.
doi: 10.7498/aps.38.1510
Abstract +
A perturbative calculation for the long-range and intermediate interactions between excited state H2(E1∑g+) and ground state H2(X1∑g+) in the crossed geometry is performed by using a trial wavefunction depending on the interelectronic distance explicitly. According to the results, there is a potential energy barrier around the inter-molecular separation D = 6.5α0. Inside the barrier, there shows a strong chemical bond behavior.
1989, 38 (9): 1515-1520.
doi: 10.7498/aps.38.1515
Abstract +
Absolute measurements of emission cross sections have been performed for the lines from Arll excited states in Ar2++Li and Ar2++Na collision. The energy of incedent ions ranged from 40 keV to 300 keV. The dependence of the emission cross sections on the energy defect △E is discussed. We find that the processes with intermediate △E(>0) have larger cross sections. We also find that the excited states correlated to the observed lines belong to the high J quantum numbers in an electron configuration.
1989, 38 (9): 1521-1526.
doi: 10.7498/aps.38.1521
Abstract +
In a detailed study of the problem of induced numerical artifacts in the Real Space (RS) High Resolution Electron Microscopy (HREM) image simulation, a δ-ε criterion in the RS method for simulating HREM images has been derived. This condition imposes a practical limitation in choosing the sampling interval δ and the slice thickness ε for the RS method. It has been found that when the δ-ε condition is satisfied and a much more accurate formula is used for calculating the propagating factor p(r), the RS method gives results in satisfactory agreement with the conventional FFT multi-slice (FFTMS) method, but saving coputational time and avoiding the computing divergence that may arise in the RS method.
1989, 38 (9): 1527-1529.
doi: 10.7498/aps.38.1527
Abstract +
An HRTEM study was carried out for the orthoclase (Or65 Ab21 An11) taken from the augite-mozonite deposit in Wuliang, Shandong Province. The results showed that this material consists of superlattice with long period. The relationship between extended cell parameter and triclinic subcell parameter is as follows: a=atc, b = 8d010≈8btc c= ctc, β= βtc (tc represents the triclinic subcell).The orthoclase consists of a series of triclinic domains. It is the intermediate modulated structure formed in the process of phase transformation of potassic feldspar horn C2/m symmetry to C1 Symmetry through the ordering of Si and Al in the te-terahedra.
1989, 38 (9): 1530-1533.
doi: 10.7498/aps.38.1530
Abstract +
In this paper, we report the experimental and theorical results of self-transmission of pi-cosecond light pulses of 1 μm in undoped semi-insulating GaAs at Brewster angle incidence. The best fitting density of the deep level EL2 is 1.2×l016cm-3, the two-photon absorption coefficient is 29 cm/GW and the free-carrier cross section is 2.7×10-17 cm2.
1989, 38 (9): 1534-1539.
doi: 10.7498/aps.38.1534
Abstract +
Ce has been introduced into single crystal Si by means of vacuum deposition of Ce onto Si wafer, and then annealing at 1050℃ for 20 hours in vacuum.In the annealing process, Ce-Si alloy was formed on the surface at first, and then the Ce atorms diffused into Si and produced a diffusion region of Ce with thickness about 4.5 μm. The concentration profile of Ce was determined by SIMS. The diffusion coefficient of Ce in Si at 1050℃ was obtained as 3.9×10-13 cm2/s. The average resistivity ρ of the Ce diffusion layer was measured from 77K to 450K.
1989, 38 (9): 1540-1544.
doi: 10.7498/aps.38.1540
Abstract +
Considering the phonon absorption and the phonon emission, we solve the equation for average energy loss rate of carriers and the hot phonon Boltzmann equation. We find that τavg is a sum of the electron phonon interaction time constant and the nonequilibrium phonon. decay time.
1989, 38 (9): 1545-1550.
doi: 10.7498/aps.38.1545
Abstract +
A theory describing the resonance fluorescance of atoms in strong magnetic field is proposed. A general expression of spectrum distribution for this resonance fluorescence is given and the relation between the spectrum and the magnitude of the magnetic field is examined.
