Vol. 29, No. 7 (1980)
1980-04-05
CONTENT
1980, 29 (7): 813-828.
doi: 10.7498/aps.29.813
Abstract +
When the target is a grey body, especially when its temperature is nearly equal to that of circumferential bodies, the target's self-radiation and the circumferential radiation reflected by the target must be considered. Thus, the sensibility equations of various infrared systems have to be modified. According to these modified equations, we can explain some experimental phenomena that-can not be interpreted by the unmodified equations in which only self-radiation is taken into account.Here we discuss the thermal imaging systems in detail and the effects of following factors on them. These factors are: the temperature differential emissivity differential and reflectivity differential of adjacent detecting elements in the scene and the scanning efficiency scanning superposition ratio series or parallel arrangement of detector arrays additional field lens or immersion lens and so on. Then, we obtain the more complete sensibility equations and the formula of the noise equivalent temperature differential NETD for thermal imaging systems. The calculation methods of XT in NBTD are described and the numerical tables of XT are given.
1980, 29 (7): 829-835.
doi: 10.7498/aps.29.829
Abstract +
The emissivity of various room temperature materials may be measured simply by the HD Infrared Low Temperature Radiometer, the results of the measurement are in agreement with those of other articles.When the radiation temperature of various room temperature materials is measuredit is found that values obtained are nearly all the same. In order to explain these experimental results, the corresponding formulas are deduced, in these cases, the reflective radiation must be considered.
1980, 29 (7): 836-842.
doi: 10.7498/aps.29.836
Abstract +
The characteristics of the crystal field in A3B type compounds with A-15 structure are considered, the relative displacements △E⊥ between d-electron energy levels for atom A are calculated according to the pair potential model, and an improved RCA energy band model is further suggested based on the LCAO method. By following this approach, the dependence on △E⊥ of the superconducting critical temperature of the V3B compounds is obtained. The theoretical results are in rough agreement with experimental data.
1980, 29 (7): 843-849.
doi: 10.7498/aps.29.843
Abstract +
In the present paper, the analyses for the numerical solution of the Eliashberg equation and the Tc formula of Type A superconductor, which were presented in the previous paper of this series, are extended to the case of μ*≠0.
1980, 29 (7): 850-859.
doi: 10.7498/aps.29.850
Abstract +
Low frequency internal friction in the process of plastic deformation of Al-Cu and Al-Mg alloys was measured on a small tensile test machine and a series of internal friction jumps was observed on the internal friction-strain curve. A study was made on the effect of temperature of measurement and some metallurgical factors on these internal friction jumps. Experimental results showed that the range of the temperature of measurement within which these internal friction jumps appeared corresponds tc that for the appearance of the serrated stress-strain curves of aluminium-copper alloys. This indicates that these internal friction jumps on the internal friction-strain curves are associated with the process of strain aging occured in the process of plastic deformation, i.e., they are originated from the alternate anchoring of dislocations by atmospheres of solute atoms and their subsequent escaping in the course of plastic deformation.
1980, 29 (7): 860-866.
doi: 10.7498/aps.29.860
Abstract +
In this article, infra-red microscopy and etching method were used to study the morphology of the copper precipitates in silicon crystals. It was found that a variety of copper precipitates observed by ir microscopy consists of precipitated disks laying in {110} planes and their morphology bears no relation to the properties of the sample.
1980, 29 (7): 867-877.
doi: 10.7498/aps.29.867
Abstract +
Infrared Absorption measurements of oxygen in silicon and germanium were made with IE Fourier Transform Spectrometer at temperatures between 6 K and 300 K in the region of 400-4000cm-1. Resolution was up to 0.5cm-1 when high resolution conditions were adopted.Detection limit and sources of error on oxygen concentration of silicon and germanium determined by infrared absorption measurement at low temperature were identified. Using a 2 cm thick sample, the- lower limit of detectability for oxygen at 20 K is estimated to be 9.6×1014 oxygen atom. cm-3 and 3.0×1014 oxygen atom. cm-3 in silicon and germanium respectively. The oxygen concentration of CZ germanium single crystals with different growth conditions was also studied and these results determined by IE measurements havebeen investigated and discussed at temper-lithium precipitation technique.Temperature-dependent fine structure of 1106 cm-3 absorption band of silicon with different oxygen concentration have been investigated and discussed at temper atures between 6 K and 300 K.
1980, 29 (7): 878-888.
doi: 10.7498/aps.29.878
Abstract +
In this article, we derived the transformations among three sets of elosed time path Green's functions and some calculation rules, from which a general definition of arbitrary multipoint retarded and advanced Green's functions follows naturally. Some algebraic identities among multipoint functions have shown to be the consequences of the property W[J+,J-](J+=J-=J)=0 for the generating functional on the closed time path.
1980, 29 (7): 889-896.
doi: 10.7498/aps.29.889
Abstract +
The paper describes the condition of forming α-FeOOH in the alkaline solution and tlie various factors that influence the phase composition.
1980, 29 (7): 897-904.
doi: 10.7498/aps.29.897
Abstract +
In this work, the exact result of the problem of four-wave mixing in resonant absorbing media has been obtained. The effects of the degenerate four-wave mixing in the Nd3+: glass were calculated, the theoretical results agree well with the experimental measurement.
1980, 29 (7): 905-915.
doi: 10.7498/aps.29.905
Abstract +
In order to predict the characteristics of CO laser, usually nearly a hundred stiff. differential equations must be solved numerically. Thus it is of interest to make an analytical approach to this subject. Starting from basic governing equations for vibrational-distribution function and radiative intensities, we have deduced the gain-satura. tion relation of a steady CO laser, we consider the general oase in which both homogeneous and inhomogeneous broadening exist simultaneously for the radiative transiticn. The effects of multilevel cascade emission is elucidated. For two special cases of twolevel emission and homogeneous broadening limit, the present results are in agreement with the theories presented in references [9] and [4], respectively.
1980, 29 (7): 916-926.
doi: 10.7498/aps.29.916
Abstract +
A nonlinear dispersion relation is derived for the homogeneous, magnetized plasmas by the conventional "ponderomotive force" method. By using this unified dispersion relation, various parametric instabilities (stimulated anomalous absorptions and scatterings) are discussed. The results are compared with those obtained by other authors in detail. In the validity region of this model ωidler《 ωpump), the results derived by previous authors can be recovered. In addition to obtaining a few instabilities which have not been appeared in literature, we also find that in general:1. the "dipole approximation" can give the right results for the stimulated anomalous absorption problems,2. the magnetic field may enhance the plasma stability.
1980, 29 (7): 927-936.
doi: 10.7498/aps.29.927
Abstract +
Cerenkov effect in gas medium is discussed. It is pointed out that the relativistic electrons with isotropic distribution of velocity, when moving through a dense gas, will produce the broad atomic emission-lines with a remarkably asymmetric profile, the continuum slope on its long wave side being quite flat and that on the short wave side very steep.Calculation for the hydrogen atom shows that the width of Lα line may be larger than 60? as the gas density reaches N = 5×1020cm-3. According to this radiation mec-. hanism, the emission-line spectra of QSOs can be interpreted satisfactorily.
BRIEF REPORT
1980, 29 (7): 937-939.
doi: 10.7498/aps.29.937
Abstract +
Phase conjugation of forward-wave produced by degenerate four-wave mixing by using nearly resonantly enhanced nonlinearity in orgnic dye solutions. was investigated. Good-quality reconstructed images have been obtained by direct wave-front phase conjugation. Reconstructed images with a resolution of 6 lines/mm were obtained. For rhodamin 6G in alcolol solution of 2.5×10-5 mole, nonlinear reflection coefficient up to 10% has been obtained.
1980, 29 (7): 940-944.
doi: 10.7498/aps.29.940
Abstract +
The shear viscosity of concentrated aqueous solution of polyacrylamide is so high that, according to the classical theory of the aioustic absorption, ultrasonic vibration can not propagate in it at all. However, our experiment with ultrasonic wave of frequency 11.4 MHz finds that it exhibits ultrasonic absorption with the same order of magnitude as water does. This paper gives a qualitative explanation about the great difference between theory and experiment on the ground of molecular structural feature of this kind of solution.The measurements of the ultrasonic absorption of acrylamide aqueous solution with various concentrations have also been carried out. By comparing the experimental results of the two solutions it can be considered that the excessive ultrasonic absorption of the polyacylamide solution comes from the characteristic behavious of the solute macromolecules themselves.The ultrasonic velocity and density of these two solutions are also investigated. From them the concentration curves of compressibilities has been calculated and it is found that some atomic groups in the solute molecules exhibit the same hydrate behavior in the aqueous solution independent of whether they are in polymer or in small molecular substance.
1980, 29 (7): 945-949.
doi: 10.7498/aps.29.945
Abstract +
We have measured the M?ssbauer spectra of α-FeOOH with various particle sizes, and have studied the change of the line shapes of the M?ssbauer spectra during the process of phase transformation. In our opinion, the asymmetric line shapes of the M?ssbauer spectra of α-FeOOH is mainly due to defective crystal structure.
1980, 29 (7): 950-955.
doi: 10.7498/aps.29.950
Abstract +
The coherent radiation of ten species, F,Ne,N2,N2+,XeF,XeCl,XeBr, KrF, KrCl, ArF were obtained by using a high pressure UV pre-ionization dischage device and varing lasing gases in a laser. The laser parameters and the output behaviour were also given.
1980, 29 (7): 956-960.
doi: 10.7498/aps.29.956
Abstract +
A new method for level slicing operation of optical images, utilizing the nonlinear characteristics of photographic film and the complementary properties of the positive-negative is described. The mathematical model of the characteristics curve is proposed, and the relation between the contrast of level slicing, the γ value and the exposure is discussed. The experimental results are presented. The advantage of this method is that it employs noncoherent source and is very simple.
