Vol. 33, No. 12 (1984)
1984-06-20
CONTENT
1984, 33 (12): 1629-1639.
doi: 10.7498/aps.33.1629
Abstract +
In this paper, we have calculated the energy levels and wave functions, selection rules of two-photon fransition and two-photon magnetoabsorption of narrow-gap semiconductor in a magnetic field. The comparison of theoretical result and experimental spectra is given.
1984, 33 (12): 1640-1649.
doi: 10.7498/aps.33.1640
Abstract +
In this paper, the third order optical nonlinearity of narrow-gap semiconductor near two-photon resonance in a magnetic field is discussed. The theoretical positions and relative strengths of the peaks of nonlinear Faraday rotation and Voigt phase shift near the gap edge are obtained.
1984, 33 (12): 1650-1660.
doi: 10.7498/aps.33.1650
Abstract +
A careful analysis of the boundary effects on the eigenstates of a disordered system when it is embeded in an ordered system was carried out. It was found that the properties of the system in the region whose distance from the boundary is greater than the localization length of the system can be reproduced. This then suggests a convenient way to study the eigenstatea of disordered systems.
1984, 33 (12): 1661-1672.
doi: 10.7498/aps.33.1661
Abstract +
The Langevin quantum theory has been used to treat the optically pumped three-level laser system. We derive an equation of motion for laser field in the type of Van der Pol equation when the photon number of the laser field is not too high. It includes not only both incoherent and coherent pumping, but also both strong and weak optical pumping. If an average over reservoir is taken, the equation will give all the semi-classical results. Our results show that the laser gain comes from two basic processes, i.e., a two-photon process and a two-step process. When the pumping strength is larger than some value, the dynamic Stark effect will appear. The laser linewidth is mainly contributed by the thermal noise, the vaecum fluctuation, the spontaneous emissions between the laser levels and the spontaneous Raman scattering.
1984, 33 (12): 1673-1679.
doi: 10.7498/aps.33.1673
Abstract +
When two microwaves with frequencies close to each other are applied simultaneously to a 87Rb gas cell, which is optically pumped by 85Rb lamp, the beat in the resonance signal of 0-0 transition of 87Rb gro und state is observed. Theoretical explanation is presented.
1984, 33 (12): 1680-1686.
doi: 10.7498/aps.33.1680
Abstract +
The FID arising from the quadrupole interaction is broken into a rotational echo train under the slow rotation condition, and the number of these echoes increases when adjusting the angle between the rotational axis and the applied magnetic field towards the Magic Angle. Thus, a accurate and quick setting of the Magic Angle in MAS-NMR experiments can he easily obtained by this phenomenon. It is theoretically explained by analysing the FID of a spin-1 system. The setting accuracy within 0.05°with a per-deuterated HMB sample is experimentally demonstrated.
1984, 33 (12): 1687-1692.
doi: 10.7498/aps.33.1687
Abstract +
Symmetry determination by CBED has been carried out for LiZnTa3O9 and LiGaTa3O9 crystals, which were first grown in our laboratory, LiZnTa3O9 is rhombohedral with lattice parameters, a=0.557 nm, a=56.12°,The point group is 3m and the space group is R3c. LiCaTa3O9 is tetragonal with lattice parameters a=0.778 nm, c=0.783nm. The point group is 4/mmm.
1984, 33 (12): 1693-1699.
doi: 10.7498/aps.33.1693
Abstract +
The effect on amplitude of EXAFS from harmonic caused by high order diffraction of crystal monochromator is discussed. The general expression and calculated results are presented. It is shown that the harmornic decreases the amplitude of EXAFS and the amount of decrease is related to such factors as intensity ratio of harmonic to fundamental, thickness and absorption coefficient of specimen. K edge EXAFS spectra with and without harmonic for different thickness copper foils have been measured respectively, and the distortion of single shell EXAFS amplitudes have been extracted. The measured results are consistent with calculated ones. Consequently, a method to correct the harmonic effect on EXAFS amplitude is proposed.
1984, 33 (12): 1700-1706.
doi: 10.7498/aps.33.1700
Abstract +
The ionic conduction in polycrystalline Li3+xV1-xTxO4(T=Si, Ge) has been studied by using AC impedance method. It was found that some processing conditions, such as forming pressure, sintering time and sintering procedure have great effect on ionic conductivity. The attention was focused on the physical origins of these effects. The best specimens could be prepared under forming pressure about 8t/cm2 and continual sintering at 1000℃ for 5 to 6 days. The temperature fluctuation should be avoided during sintering process. We found that, at 25℃, the bulk ionic conductivities of polycrystalline Li3.5V0.5Ge0.5O4 and Li3.3V0.7Si0.3O4 prepared under optimal conditions are 2.2×10-5Ω-1cm-1and 1.9×10-5Ω-1cm-1 respectively.
1984, 33 (12): 1707-1712.
doi: 10.7498/aps.33.1707
Abstract +
The grown condition in aqueous solutipn,morphology and polarity of 2KIO3·HC1 single crystal were studied. The transmissivity, the position of optical indicatrix in the crystal and the indices of refraction were determined and discussed. The phonomenon of phase match SHG of 1.06μm from YAG laser was observed. Its pyro- and. piezoelectric, dielectric characteristics and conductivity were determined. The anisotropy of the single crystal is interest.
1984, 33 (12): 1713-1718.
doi: 10.7498/aps.33.1713
Abstract +
The interactions of H2O and O2, with InP clean surface in the high vacuum chamber have been studied by means of Auger electron spectroscopy. It has been found that the water vapor plays a significant role responsible to the electron stimulated adsorption of oxygen than the pure oxygen. The In and P Auger signals change substantially during the oxygen adsorption process which is accessible as an occurence of electron stimulated oxidation (ESO). The oxygen atoms bond only with surface In atoms but not with P at the earliest stage, then they penetrate into the bulk and conbine with both In and P continually making the surface layer convert into oxide with an almost constant oxidation rate. As compared with the Auger depth profiling of InP native oxides, the similarity of the ESO and the ordinary oxidation processes is obvious. But the electron stimulated adsorpted oxygen could not fully oxidize the phosphorus in the surface layer while thermal oxidation and anodic oxidation do, the P concentration in the ESO oxide is higher than that in the thermal oxide but lower than the anodic oxide.
1984, 33 (12): 1719-1727.
doi: 10.7498/aps.33.1719
Abstract +
The correlation bunction of inhomogeneous electron system at the metal surface has been calculated in the Hartree-Fock approximation.
1984, 33 (12): 1728-1732.
doi: 10.7498/aps.33.1728
Abstract +
We found exact expessions for the electromagnetic fields associated with Kerr-Ne-wmian-Kasuya black holes (rotating Dyon black holes) in a magnetic universe. In the particular ease of charge Φ0J, exact expressions for the gravitational field were also obtained.
1984, 33 (12): 1733-1739.
doi: 10.7498/aps.33.1733
Abstract +
The concentration profiles of high-dose implanted N+ (5×1017 atom/cm2, 100 keV) in iron foils (about 4000? thick) and iron bulk sample (industrial purity) were measured by E. B. S. via α-particle of energy in order of MeV. A dip was found in backscat-tering spectrum of the substrate, as a result of the high-dose impurity, implantation a method was developed to calculate the concentration profile of impurity based on the dip.
STUDY ON THE POLARIZATION MECHANISM OF THE BEAM-FOIL INTERACTION IONS BY USING THE CHANNELING EFFECT
1984, 33 (12): 1740-1744.
doi: 10.7498/aps.33.1740
Abstract +
In order to provide an experimental evidence for the controversial polarization mechanism of the beam-foil ions, He+ ions with energy of 1 MeV have been used to pass through a single crystal gold foil along the 〈110〉direction, and random direction, and the Stokces parameters of Hell 4686? 4f→3d transition have been accurately measured.
1984, 33 (12): 1745-1752.
doi: 10.7498/aps.33.1745
Abstract +
A new method of analysing positron annihilation lifetime spectra in the fraquency domain by Fourier transform is proposed. Some characteristics of the transform of the positron annihilation spectrum and the potential advantages of this method are briefly discussed.
BRIEF REPORT
1984, 33 (12): 1753-1758.
doi: 10.7498/aps.33.1753
Abstract +
In this work, the time effects and superconductivity in the process of phase transition in InSb films condensed at low temperatures are studied. The following important experimental results are obtained: (a) Between occurrence of the first and the second conductance jump, the film samples are in the same amorphous metallic state, and have the same superconducting transition temperature Tc. (b) The relationship between Tc and annealing temperature ta is very similar to that between conductivit σ and Ta. (c) After the second jump, the conductance decreases, during the process of super conducting transition in certain transition zone R(T), the samples transform gradually from perfect to partially superconducting, (d) There are obvious time effects in the process of phase transition.
1984, 33 (12): 1759-1764.
doi: 10.7498/aps.33.1759
Abstract +
By applying Gilkey's result, we obtain the coefficient α3 in DeWitt-Schwinger proper time expansion of the Green function for scalar, spinor and vector fields respectively, so finally we succeed in obtaining the renormalized vacuum stress-energy tensor for deSitter space-time in large mass approximation.
1984, 33 (12): 1765-1770.
doi: 10.7498/aps.33.1765
Abstract +
Optical rotatory dispersion of LiKSO4 crystal was pleasured at room temperature. The "crystal" nsodel of optical rotation fits well to the experimental results. In the temperature range from -180℃ to 680℃, four phase transitions were observed by means of optical rotation measurement: Phase F3 Phase F2 Phase F1 Phase X670℃→Phase α. The two transitions at low temperatures show obvious temperature hysteresis. All the transition temperatures are different from sample to sample. The relation between the transition sequence shown above and the data reported in literatures is discussed.
1984, 33 (12): 1771-1775.
doi: 10.7498/aps.33.1771
Abstract +
Polypyrrole films doped with BF4-,HSO4- and ClO4- were prepared by electrochemical method. Electrical conductivities of these samples and their temperature dependences were measured by four-probe method and VSC (voltage shorted compaction) method respectively. Experimental results indicate that the apparent temperature dependence of the conductivity as obtainted by the usual four-probe method, exhibits the character of typieal semiconductor, this feature is due to the contact resistance in the interblock or intergranular regions of the film. The measurement cannot reflect the true conductivity intrinsic to the doped polypyrrole film. However, the method devi-ced to short circuit the intergranular contact resistance does actually show the metallic temperature dependence of the conductivity of doped polypyrrole film, its conductivity increases with decreasing temperatures.When the polypyrrole film doped with BF4- was .partially reduced electrochemi-cally to a room temperature conductivity of 6-9 (Ω·cm)-1, the film exhibit a metal-semiconductor transition at 100 K as obtained by VSC measurement. IR-spectra indicates that the polypyrrole chain undergo certain structural changes during the electrochemical reduction process.
