Vol. 43, No. 3 (1994)
1994-02-05
ATOMIC AND MOLECULAR PHYSICS
1994, 43 (3): 345-350.
doi: 10.7498/aps.43.345
Abstract +
In this paper a detailed method is given to calculate atomic average of ionization in relativistic Hartree-Fock-Slater self-consistent field scheme. As an example，culculations are presented for the Au and Cu atoms at several temperatures (from 20eV to 20keV) and matter densities (from 0.1 D０ to 100D０). The variation of thedegree of ionization following the change of temperature and matter density are discussed.
1994, 43 (3): 351-355.
doi: 10.7498/aps.43.351
Abstract +
The potential energy curves for six electronic states, X2∑+，Ａ2∏i，Ｂ2∑+，Ｃ2∏i，Ｄ2∑+ and Ｅ2∏r of the linear ArCN molecule have been calculated at the ROHF level with the 6-31G* and 6-31G?* basis sets, respectively. The calculation (ROHF) results for the electronic states of ArCN indicate that it is an exciplex. The UHF calculations for the X2∑+ and Ａ2∏i states demonstrate that big spin contaminations in the UHF wavefunctions do not influence the shapes of these two potential energy curves.
1994, 43 (3): 356-368.
doi: 10.7498/aps.43.356
Abstract +
The dynamics of isotopically selective interactions between the radiation of three pulsed lasers and atoms with a four-levels scheme has been studied. Starting from the time-dependent Schr?dinger equation with the rotating-wave approximation, we applied Sylvester theorem to the dynamic equations associated with near-and off-resonant excitations, respectively. We obtained the explicit expressions for the four-levels occupation probabilities. The analytic treatment explored the properties of coherent oscillations occurred in the atomic excitatioi. processes with intense mono-chromatic lasers. The conditions under which the population inversion takes place are derived from near-resonant excitations. The criteria to select the basis parameters of pulsed lasers involved in the process are also provided.
1994, 43 (3): 369-379.
doi: 10.7498/aps.43.369
Abstract +
The interseries interaction of the Mg 3pnd J=3 autoionizing Rydberg series has been studied using multichannel quantum-defect theory. Its impact on the excitation profiles and the autoionization rates has been investigated. The behaviors of the Mg atom and the continuity of the electron's wavefunction near the ionization threshold are examined. The agreement between the calculated antoionizing spectra and the experimental ones is found to be satisfactory.
1994, 43 (3): 380-388.
doi: 10.7498/aps.43.380
Abstract +
A time-of-flight (TOF) spectrometer has been developed to measure the absolute total cross sections for electrons scattering with helium and other gases over energy range from 1 to 50 eV. The TOF spectrometer and experimental procedures are described in detail, and the experimental results for electron-helium scattering are presented, together with associated errors. The results are found to be in good agre-ement with other recent experimental and theoretical results.
CLASSICAL AREA OF PHENOMENOLOGY
1994, 43 (3): 389-394.
doi: 10.7498/aps.43.389
Abstract +
The equations of atomic density matrix are solved without any approximation when the strong:ignal field and external coherence-driving field are detuned to respective dipole-allowed transition of the Λ atom in such a way that Δ1=-Δ2. Under the equal Rabi frequency (G) condition, it is found that approximate, coherent population trapping appears for small detuning, which leads to the transparency of the medium to the strong signal having an order of Ｏ（Ｇ-3）. If the detuning is G/2, the atom nearly equally populates three levels and the transparency is of only order Ｏ（Ｇ-1）.
PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES
1994, 43 (3): 395-403.
doi: 10.7498/aps.43.395
Abstract +
The plasma energy and particle confinement could be improved by LHCD in HT-6B tokamak. A multichannel La monitoring system was used for the measure-ment of particle oonfinement in the experiment. The particle confinement time has been increased two to six times by LHCD. There is no apparent relation between the τp increment degree and the input LHW power (10-60 kW). But there is a good correlation between the appearance of improvement and the appearance o: the energetic electrons caused by LHCD. With the measurement of emissivity ratio of OII 441.8 nm and OII 446.6 nm within the plasma edge(r=8.5-11.0 cm for α=12 cm). We discovered that, when improvememt happened, the gradient of electron temperature in plasma edge increased, the same tendency of the change“in the case of H-mode.
1994, 43 (3): 404-410.
doi: 10.7498/aps.43.404
Abstract +
The feasibility of using ECRH to produce sloshing electrons and to form tandem mirror thermal barrier is experimentally studied, and the measurement of plasma potential is presented. Results show that production of sloshing electrons to form thermal barrier by ECRH, is successful.
CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES
1994, 43 (3): 411-415.
doi: 10.7498/aps.43.411
Abstract +
A new method of background correction of SAXS intensities scattered by the aged metallic glass is proposed. The intensities scattered by the as-quenched sample were taken as the background scattering. This mothod was applied to the background correction of the SAXS intensities scattered by Cu 73Sn6Ni6P15 metallic glass aged at 473 K for 4hs. Porod constant Ｋ′p＝４．６×１０-2（ｎｍ-3）,Qs＝１．６３（ｎｍ-2）, specific inner surface Ｓp＝８４ｍ2／ｃｍ3, and Porod's radius of the crystalline particle Ｒp＝４．４ｎｍ were obtained by using this method of backgroud correction.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
1994, 43 (3): 416-423.
doi: 10.7498/aps.43.416
Abstract +
In the framework of the single-electron tight-binding Hamiltonian, we numerically calculate the electronic spectrum, integrated density of states, and investigate the localization of the electronic states by the use of the generalized first moment, generalized second moment, and the inverse paticipation ratio. It is found that there is no normal degenerate states, and only accidentally degenerate states. Furthermore, all of the states are intermediate ones, there is not any extended state or localized state.
1994, 43 (3): 424-432.
doi: 10.7498/aps.43.424
Abstract +
The studies about the electronic structures of Si3N4 and Si crystalline quantum dots by the tight-binding approximation and the recursion method are presented, in which spherical clusters with high symmetry and optimized surface are used as models of the quantum dots. The variations of the positions of the top of valence band and the bottom of conduction band following the size change of guantum dot are given. The local and average densities of state (DOS) of the central atom in 328-atom Si3N4 quantum dot and 323-atom Si quantum dot have been calculated, and the relations between DOS and spectral structures have been discussed. From the discussions, it is concluded that local DOS of central atom can give good descriptions of optical spectra of quantum dots. which has been proved by experimental results.
1994, 43 (3): 433-437.
doi: 10.7498/aps.43.433
Abstract +
A new variational method for solving polaron problem is suggested, and the nonlinear differential-integral equation satisfied by variational solution of plolaron has been derived, the numerical result of which is as anticipated by earlier. works.
1994, 43 (3): 438-449.
doi: 10.7498/aps.43.438
Abstract +
The formula of one-electron theory for the circulating currents in normal metal hollow cylinders, threaded by magnetic flux of Aharonov-Bohm type, is proven. The form of it is independent of either the shape of cylinder or the properties of carriers (charge and mass). The exact solutions of energyeigen values and wave-functions have been obtained for the perfect lattice case. We have also studied the periodicity of currents varying with the magnetic flux and the increasing tendency of current amplitudes with the height and thickness of cylinder wall. A number of new results have obtained in this work.
1994, 43 (3): 450-457.
doi: 10.7498/aps.43.450
Abstract +
The intermetallic compound ＮｄＦｅ10Ｍ2Zx(M一Mo, Cr, Z一C, N) were prepared by gas-solid reaction of fine powder of parent alloys in purified C2H2 or N2 gas. Then the structure and intrinsic magnetic properties were studied. The contribution of different interstitial atoms is different for magnetic properties of ＮｄＦｅ10Ｍ2 materials. ＮｄＦｅ10Ｍ2Zx exhibits uniaxial anisotropy. The M?ssbauer effect is also studied.
1994, 43 (3): 458-464.
doi: 10.7498/aps.43.458
Abstract +
Intrinsic properties and M?ssbauer effects of the compounds in Sm2Fe17-xMoxC system were investigated. The substitution of Mo for Fe led to an increase of Tc, HAand iHc with a maximum at about x = 0.6. M?ssbauer analysis showed that the Mo atoms preferentially occupied the 18h sites in the Th2Zn17 structure.
1994, 43 (3): 465-475.
doi: 10.7498/aps.43.465
Abstract +
The dynamic studys of the lattice vibrational behaviors and hyperfine interactions on the Bi-based high-Tc superconductors are conducted by means of M?ssbauer measurement. The recoilless fractors show that there is a significant lattice softening on Cu-O layers, above superconducting temperature, around 120 and 200K respe-ctively. Such anomalous behavior is thought to be a precursor effect of supercondu-ctivity. The recoilless fractors and the isomer shifts show that the Debye tempera-ture ΘD=310-350K. Based on the measurement of isomer shift, quatrupole spli-tting and spectroscopy width. it can be seen that both softening of lattice vibrational modes and delocalization effect on d-electron orbits exsist.
1994, 43 (3): 476-482.
doi: 10.7498/aps.43.476
Abstract +
Using Gaussian decomposition method, we theoretically analysed Z-scan in thick optical nonlinear media. Useful results are obtained for experimenters searching high performance optical nonlinear materials and designing optical limiter.
1994, 43 (3): 483-493.
doi: 10.7498/aps.43.483
Abstract +
Based on the universal additivity law of the interference light an analytic representation for the relation between the enhanced Kerr rotation θk and the intrinsic Kerr rotation θ0k of the magneto-optical materials is obtained theoreticallv for a bila yer films-the difference between the measured herr rotation θk and intrinsic Kerr rotation θ0k is pointed out for the case where an incident fight goes through the glass substrate onto the magneto-optical film, a simple method for measuring the intrinsic of Kerr rotation θ0k is given. 4) the physical reason about the enhancement Kerr ro tation θk by the dielectric medium is discussed, and the reprcsrntation of the enhanced Kerr rotation θk for a bilayer system with plasma absorption edge is deduced theoretically.
1994, 43 (3): 494-498.
doi: 10.7498/aps.43.494
Abstract +
The typical Raman spectrum from light-emitting porous silicon shows a sharp peak near 520cm－１. The peak wavenumber decreases with the increase of porosity. The lineshape analysis shows that both phonon confinment and strain effects in nanocrystal silicon must be taken into account for the measured Raman spectra. The strain in porous silicon film is estimated and the result is consistent with that given by X-ray diffraction studies. No light scattering from amorphous phase is observed.
1994, 43 (3): 499-504.
doi: 10.7498/aps.43.499
Abstract +
Porous silicon of low porosity was oxidized in boiling HNO3 solution. Photo-luminescence, microluminescence and SEM studies show that the stability and the uniformity of the sample were greatly improved by such a treatment. This is a new method much easier to control than rapid thermal oxidation.
1994, 43 (3): 505-515.
doi: 10.7498/aps.43.505
Abstract +
An important feature for light ions with low energy is that their transport behaviour might be determined by a simple parameter, We have found that the ion scaled transport cross section a, is such a parameter. The one to one corresponde-ace between a, and ion transport behaviour reflects the inherent similarity among some ion target-energy combination. In the present paper, the definition of the scaled transport cross section is given, and the theoreilcal basis of the scaled parameter determining ion transport behaviour is formulated. Furthermore, the interesting fea-ture has been checked and verified by our numerous transport calculations. Two empirical formulae for particle reflection coefficient and average projected range are given, in which the scaled transport cross section is taken as argument.
INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY
1994, 43 (3): 516-520.
doi: 10.7498/aps.43.516
Abstract +
The effects of interchain coupling on the energy spectra and the localized modes around soliton have been studied based on a generalized SSH model including the interehain electronic transfer term. Duo to the interchain coupling, the soliton level shifts from the center of forbidden gap, and the symmetry of energy spectra is destroyed. The localized modes obtained from SSH model are splitted and their frequencies are changed. Besides, the change of freqencies is also related to the different relative ordering of the two neighboring chains, and different solitons in the two chains.
