Vol. 43, No. 8 (1994)
1994, 43 (8): 1217-1225. doi: 10.7498/aps.43.1217
The effect of gravitational waves (GW) on phonon in axisymmectic non-uniform elastic medium is analysed by means of the complex coordinate in Serebryany's complex space. and expression of diving force produced by the GW and corresponding phonon soluitons are given. In our solution forms. they are shown that the GW propagating along symmetric axial direction generates only perturbation to radial and tangential components of the phonon fields. while the GW propagating along direction perpendicular to the symmetric axis generates perturbation to all components of the phonon fields. i.e., radial, tangential and axial components. The strength of pertur-bation depends on concrete form of radial distribution function of shear modulus and the GW's amplitude. Moreover, above results are compared with the GW's perturbing effect in topological phonon space with the spiral dislocation.
1994, 43 (8): 1226-1227. doi: 10.7498/aps.43.1226
In this note, we show that the conclusion of Li Cheng-Yao i.e. is erroneous.
1994, 43 (8): 1228-1233. doi: 10.7498/aps.43.1228
Fundamental limits on the minimum size Nｍｉｎ of data set is an important problem in estimating the dimension D of attractor using Grassberger-Procaccia algorithm. We modify the results of Smith (1988), Eckmann and Ruelle(1992), and suggest a new criterion Ｎｍｉｎ >21/2·((27.5)1/2)D
1994, 43 (8): 1234-1240. doi: 10.7498/aps.43.1234
We studied the effective region of parameters where a numerical method for finding all periodic orbits of the dissipative Henon map can define a good symbolic dynamics, and analysed the special expression appearing next to the critical curves of bifurcations.
THE PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
1994, 43 (8): 1241-1245. doi: 10.7498/aps.43.1241
Some important physical effects appear due to molecular short range correlations in nematic liquid crystals. When the orientational pair potential including the higher order terms, recent theories are not yet able to give reliable calculations. This paper is devoted to developing a new numerical method to solve the equation for equili-brium state, based upon the cell theory. We do not use any empirical expansions for the orientational distribution function but obtain the accurate molecular orientational distrbutions. Then we give the accurate numerical results of the order parameter at the phase transition, the entropy change etc., and obtain the correction for the Sene-ralized mean field theory made by the short range correlations.
ATOMIC AND MOLECULAR PHYSICS
1994, 43 (8): 1246-1253. doi: 10.7498/aps.43.1246
The steady-state properties of a spin system irradiated by RF field are analysed. The steady-state NOE experiment is described by the extended Solomon equations. The steady-state NOE enhancement factor is obtained and verified by the experiments of liquids and solids.
1994, 43 (8): 1254-1261. doi: 10.7498/aps.43.1254
By making use of collins model and taking Ar as an example, we calculated the thermodynamical function of liquid taking into account of the existence of vacancies, studied the critical point, Boyle temperature, Boyle Curve under the codition of motionlessness, translation and anharmonic vibration of atoms. The results obtained are close to experimental values and the results from empirical equation.
CLASSICAL AREA OF PHENOMENOLOGY
1994, 43 (8): 1262-1267. doi: 10.7498/aps.43.1262
We use the numerical method to study the influences of q deformation on the quantum statistical properties of even and odd q-coherent states (E一。q-C Ss).It is shown that nonclassical properties of E-0 q-CSs are very different from those of the usual even and odd coherent states (ECSs, OCSs). It is found that squeezing effect appears for both even and odd q-CSs and has quasiperiodicity, and the antibunching effect may appear for even q-CSs but disappear for odd q-CSs in some range of the parameters q and r.
1994, 43 (8): 1268-1280. doi: 10.7498/aps.43.1268
In this paper the amplification equation of solitons propagating in Er3+-doped optical fibers is established by using the semi-classical theory. This equation takes into account of pump excited-state absoption so that it is applicable to the pump wavelength regime of 0.5-1.49μm. This equation is also applicable to the optical fibers with abitrary refrective index profile. abitrary pump and signal optical wave modes, abitrary doping contribution，homogeneous and inhomogeneous broadening and lumped and distributed amplification, which is a necessary elementary analytical equation for a profound research of tiie characteristics of soliton amplification in the Er3+-doped optical fibers and optirnizing its design.
1994, 43 (8): 1281-1288. doi: 10.7498/aps.43.1281
From the amplification equation of solitons propagating in Er3+-doped optical fibers given in reference，this paper gives the optimal pumping power for the transparent transmission in the case of distributed amplification. It is shown that the theory is in good agreement with experimental results given previously. The investigation on the optimal pumping in which excited-state absoption is considered indicates that the excited-state absoption seriously damp the pump power, but increasing the auantum transition efficiencv of around-state, can weaken the influence of the excited-state absoption.
1994, 43 (8): 1289-1294. doi: 10.7498/aps.43.1289
A new type of mode-locking laser-non cavity length matched additive pulse mode-locking laser was realized experimentally. This new kind of laser consists of an active mode-locking Nd:YAG laser and a nonlinear antiresonant ring as an end mirror. A semiconductor doped glass was used in the nonlinear resonant ring as a nonlinear element in which the nonlinear phase shift was produced when the mode-locked light pulse propagate through it. In proper conditions stable mode locking performance was got with a pulse width of 60 ps which is more than three times shorter than that from a normal active mode-locking Nd:YAG laser. The Inode-locking characteristics of this laser are presented in this paper.
CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES
1994, 43 (8): 1295-1300. doi: 10.7498/aps.43.1295
A new method with a glancing X-ray beam projected onto the sample is proposed for internal stress measurement in thin films. The curvature in 2θ versus sin2φ plot will be eliminated as the glancing angle is small enough, and the stress can be calculated in terms of the linear slope. With this method, it appears to be promise to evaluate stress distribution through the film depth as the glancing angle is changed step by step.
PRESSURE-COEFFICIENT OF RESISTIVITY AND RELAXATION UNDER PRESSURE IN AMORPHOUS ALLOYS (Fe1-xCox)77.5Nd4B18.5
1994, 43 (8): 1301-1310. doi: 10.7498/aps.43.1301
Pressure-resistivity relation of amorphous alloys (Fe1-xCox)77.5Nd4B18.5（０≤ｘ≤１．０） were investigated in detail in the hydrostatic pressure range from 0.0001 to 2.4 GPa. We obtained the variation rule of pressure coefficient of resistivity with content x in above amorphous alloys. Results show that substitution of a little Co(x=0.2) for Fe can not affect magnetic hardness and thermal stability, but enhance resistivity (about 28%)，and improve stability both of electrical and magnetic properties under high pressure. Moreover, structure relaxation were observed under 0.51GPa for 3-24 hours. Content x dependence of relaxation time of resistivity of the amorphous alloys under high pressure was studied.
STUDIES OF LATTICE DAMAGE CAUSED BY 1MeV Si+ IMPLANTATION INTO Al0.3Ga0.7As/GaAs SUPERLATTICES AND GaAs AT ELEVATED SUBSTRATE TEMPERATURE
1994, 43 (8): 1311-1317. doi: 10.7498/aps.43.1311
Rutherford backscattering/channeling technique has been used to investigate the lattice damage caused by 1MeV Si+ implantation into Al0.3Ga0.7As/GaAs superlattices and GaAs at elevated substrate temperature and room temperature for different doses. For elevated substrate temperature irradiation, a dose range for balance between defect production and dynamic annealing, and a critical dose for unbalance between them are observed for both Al0.3Ga0.7As/GaAs superlattices and GaAs. The superlattices are more difficult to be damaged than GaAs, and the critical dose for the former is also larger than that for the latter. The hot spot and knock-on model is used to interpret the temperature and dose dependence of damage accumulation in the two materials. The ralative bona strength in GaAs and ＡｌxＧａ1-xAs are calculated using CNDO/2 quantum chemistry method to explain the differences of damage accumulation in Al0.3Ga0.7As/GaAs superlattices and GaAs.
1994, 43 (8): 1318-1325. doi: 10.7498/aps.43.1318
It is needed to include the next-nearest hopping for the instability of twodimensional half-filled lattice. Then there exists a critical value δ0 of the dimerization δ. When δ≥δ0, it is part-nesting, a part of Fermi surface is flat; whereas δ＜δ0, it is only approximate nesting, Fermi surface is curved.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
1994, 43 (8): 1326-1330. doi: 10.7498/aps.43.1326
In this paper we assume that all the carbon atoms in polyacetylene lie in the ground state under conditions of the tight-binding approximation (TBA) and choose the 2Pz orbital of hydrogen-like atoms as the ground-state wavefunction of an isolated carbon atoms. A linear combination of these orbitals is used as the π-electron wavefunction of polyacetylene. On the basis of this the multicenter integral problem is studied and then the analytic solution of the transfer integral for πelectrons is obtained.
1994, 43 (8): 1331-1335. doi: 10.7498/aps.43.1331
On the basis of our previous works, we further study the dependence of the Anderson transition zone of the Aubry model in one-dimensional incommensurate systems on the wave vector. Our numerical results indicate that the Anderson transition zone is related to the wave vector; the smaller the wave vector, the lower the values of the potential strength V in which the Anderson transition zone lies.
1994, 43 (8): 1336-1343. doi: 10.7498/aps.43.1336
The dynamical process of optical-excited C60 is studied by using the tight-binding model of electron-lattice coupling and solving the real-time Newton dynamical equation. The dynamical evolutions of energy, bond structure and electron states are obtained. The theory shows that the moleule of optical excited C60 turns into a ring-bipolaron-exciton which is consistent with the self-trapped polaron exciton observed in the luminescence experiment of neutral C60.
1994, 43 (8): 1344-1351. doi: 10.7498/aps.43.1344
The γ radiation defects in shallow impurity implanted semi-insulating LEG GaAs have been studied by the deep level transient spectroscopy (DLTS) and the constant temperature capacitance transient technique. In Si-and Be-coimplanted semi-insulating LEC GaAs, there exists an electron trap Ｅ＇2 introduced by γ radiation, and both of the two original electron traps Ｅ01（０．２９８） and Ｅ02（０．３４１） are retnarkably enhanced by the radiation, by contrast, the original hole trap Ho3 is greatly reduced. There exist five electron traps,Ｅ＇01（０．２１６），Ｅ＇02（０．３４１），Ｅ＇2，Ｅ＇4 and Ｅ＇5（０．６０８）, which are caused by γ radiation in Si single-implanted semi-insulating LEC GaAs. The Ｅ01 and Ｅ＇01 are newly observed. by comparison with the GaAs grown epttaxially on a substract of GaAs with low resistivity, Si-and Be-coimplanted semi-insulating LEC GaAs possesses a smaller introduced rate of γ radiation defects, but the Si single-implanted semi-insulating LEC GaAs has a bigger one.
PROPERTIES OF MINORITY CARRIER TRAPS AND THE HOLE TRAPS IN SEMI-INSULATING LEC GaAs AFTER Si-AND Be-COIMPLANTATION
1994, 43 (8): 1352-1359. doi: 10.7498/aps.43.1352
The deep levels have been investigated by the deep level transient spectroscopy (DLTS) technique in Si-and Be-coimplanted undoped semi-insulating LEC GaAs. The four electron traps, Ｅ01（０．２９８），Ｅ02（０．３４１），Ｅ03（０．５５５） and Ｅ04（０．８２１），and two hole traps, Ｈ＇03（０．５４） and Ｈ″03（０．５７）, were observed by majority carrier pulse DLTS measurement. The DLTS signals of the two hole (minority carrier) traps possesses several interesting properties, for example, it is very difficult to make the heights of the DLTS peaks of them reach their maxima by broadening the pulse width, and the heights of the peaks depend strongly on the temperature of the samples. These phenomena can be successfully explained by the theory of the capture and thermal emission of the minority carrier at the trap. It is impossible to measure the energy levels of such two traps using the traditional DLTS technique, therefore, the hole apparent activation energies were measured to be 0.54 and 0.57eV by the constant teuiperature capacitance transient technique, respectively. The Ｈ＇03 and Ｈ″03 are newly observed defects which relate to the Si-and Be-coimplantaion in semi-insulating LEC GaAs.
INFLUENCE OF TEMPRATURE ON THE CRITICAL IN PLANE MAGNETIC FIELD RANGE FOR THE BREAK-DOWN OF VBL CHAINS
1994, 43 (8): 1360-1364. doi: 10.7498/aps.43.1360
The influence of temprature T on the critical in-plane magnetic field range for the break-down of vertical Bloch line (VBL) chains within the stripe Bloch domain walls with ordinary hardness in magnetic bubble films of LPE garnet is studied experimentally, We find that there exist two characteristic tempratures, T(1)0 and T(2)0, with the former slightly lower than the latter and both higher than room temprature Tr, such that at any T∈[Tr,T(2)0] there is a T-dependent critical range, [Hip(1)(T), Hip(2)(T)]，of in-plane magnetic field Hip: all VSLs keep stable when Hipip(1)(T)，V BLs disappear gradnally as Hip increases when Hip(1)(T)ip ip(2)(T), no VBL remains when Hip > Hip(2)(T), The lower and upper limits as well as the width of the critical in-plane field range all decrease as T increases, and the former two reach zero at T(1)0 and T(2)0，respectively. The ratio Hip(2)(T)/Hip(1)(T) tncr-eases with temperature elevating, slowly at lower T including Tr where this ratio is about 21/2 and rapidly near T(1)0. Some theoretical arguements are presented.
1994, 43 (8): 1365-1370. doi: 10.7498/aps.43.1365
That the multiple single pulse excitation method proposed in the present article can largely increase the signal-to-noise ratio of the solid-state magnetic resonance spectroscopy is analyzcd and confirmed experimentally. In addition, the application of this technique to the measurements of the central lines of half-integer quadrupole nuclei and 14N remote nuclear quadrupole resonance spectra is also discussed in detail.
1994, 43 (8): 1371-1379. doi: 10.7498/aps.43.1371
The NQR responses of the nuclear spin system with I=1 to frequency offsets and pulse widths are examined with fictitious 1/2-spin operator formalism. The transverse magnetization and longitudinal magnetization are observed with one pulse and two pulses sequence, respectively. The experimental results measured with NQR probe are consistant with theoretical calculations. It is shown that the NMR vector model can be applied to the NQR system for I=1 when the rf excitation is intro-duced on one axis in EFG principal axis frame.
1994, 43 (8): 1380-1385. doi: 10.7498/aps.43.1380
This paper presents a multi-retardation model for the complex birefringent phenomenon of an optically heterogeneous fiber reinforced composits. A multi-retar-dator matrix, and dedued from which，a group of light intensity, azimuth and retardator formula are given. Secondly, a equivalent theorem of the multi-retardators to two-retardadors is proved, which in turn leads to a point that the later should be considered as a kind of statistic equivalence of the former. The multi-retardator model can be explained briefly as follows. After having passed accross the heterogeneous medium, the emerging polarized light is of complex wave front and can be divided into a set of plane waves with different spatial frequencies, each of them being composed of a pair of orthogonal polarized rays. The coherence of all these waves at any point of any front screen prependicular to the original incident beam can be represented mathematically by the addition of their Jones vectors. Therefore, a multi-retard ator matrix resulting from the addition of Jones matrixes which are corresponding to each pairs of orthogonal polarized beam with different spatial frequency is used to characterize the birefringent behaviors of optically heterogeneous composites.
The energy levels of Pr3+ in SBN crystal are determined by means of absorption spectra and fluorescence spectra. The fluorescence band exhibits a double peak due to Pr3+ ions at different sites in SBN crystal. This shows that the multiphoton relaxation of 3Ｐ0→1Ｄ2, plays a dominant role in the radiationless transition of 3Ｐ0 state of Pr3+ ion by analysing the relation between the fluorescence lifetime and the sample temperature.