The concept of atomic or molecular coherence and its role in quantum electronics are reviewed. Coherent amplification in the material with inverted population is the result of atomic coherence. Besides, the atomic coherence effect in the two-level system manifests itself in self-induced transparency, optical nutation, and so-called photon echo. Some examples of atomic coherence effect in the three-level system are shown and their applications are discussed.
A powerful electron beam excitation of condensed noble gases opens wide possibilities for the performance of the coherent radiation sources in the vacuum ultraviolet region of the spectrum. Excitation of liquid xenon in an optical cavity by electron beam (accelaration voltage up to 700 keV and current density up to 300A/cm2) caused the stimulated emission of 1760A radiation. Narrowing of the line width of the emission spectrum down to 20A was obtained under the excitation condition of 1>30 to 50 A/cm2.
The study of the electron impact desorption of ions and neutrals from solid surfaces has been made by an increasing number of researchers. The elucidation of the mechanism allows one to check the validity of the existing concepts of the surface bonds. It is also a convenient tool for the study of the states of adsorption and the kinetics of the adsorption and desorption processes, as the desorption cross sections depend strongly on the bond strength. The model which has been proposed for the desorption of ions and the kinetics of the desorption of ions and neutrals are described. The potentiality of the ion desorption technique for the study of gas-surface interactions is described.
Photoluminescent properties of Cd4SiS6 are investigated using single crystals which are heat-treated in the atmosphere of their constituent atoms (Cd, Si, and S). As a result it is found that red and infrared emission bands in these samples are affected strongly by the Si-treatment. Nature of luminescene centers responsible for the red and infrared emissions is discussed. Furthermore, the correlation of the intensity of the red emission to that of the infrared emission is investigated, and an attempt is made to obtain adequate materials which exhibit more efficient red luminescence.
An experimental study was made to determine the effect of firing conditions and geometry on sheet resistance, TCR and current noise of palladium-silver thick film resistors. The effects of firing temperature, firing time, gas flow rate in firing furnace, temperature rise-fall rate of firing process, thickness of films fired and pattern size of resistors on the above electrical characte-ristics of resistance were investigated by using the experimental resistor paste specifically fabricated with the practical utility of the resistance performance taken into consideration. It has been found that the electrical characteristics of the resistors are significantly affected by firing temperature and time profiles in relation to the gas flow rates, and that a high performance in resistor characteristics can only be achieved by firing the paste with optimum conditions determined by each material separabely.
In this paper the kinetics of the Ge-HF-H202-H20 etching system is discussed theoretically. Assuming that the adsorption steps on the surface are in equilibrium with the reagents in solution and that the surface reaction is the rate-determining step, a rate equation of the etch-ing is derived from statistical mechanics which describes very satisfactorily the etch-rate data obtained over the entire concentration ranges studied. Moreover, the rate equation obtained gives the most important conclusion that the germanium surface atoms on which the regents are being adsorbed cannot participate in the etching. Here it is 02H- and HF2- ions that are adsorbed on the germanium surface. It is found that in this system the dependence of etch rate on crystallographic orientation is ascribed to the dependence of density of surface atoms and adsorption equilibrium constants of 02H- and HF2- ions on crystal orientation.
The measurements of ultrasonic absorption have been made in binary mixtures near the critical point. Three systems of binary mixtures composed of n-hexane-nitrobenzene, diethy-leneglycoldiethylether-water and acetonitrile-water near the critical mixture were prepared. Acoustic attenuations were measured by a pulse method over the frequency range 5-21 MHz. The temperature dependence of α/ƒ2 (where α is an absorption coefficient and ƒ is frequency) at various frequencies and the frequency dependence of α/ƒ2 at the critical point were investigated, and the experimental results were analyzed by Fixman's theory. (J. Chem. Phys. 36 (1962) 1961) The experimental results are in good agreement with the theory. Short-range correlation length l and molecular friction constant β which are characteristic parameters of the critical point were calculated from the absorption data. The results are given as follows. a) nitrobenzene-n-hexane system l=5.8Å β=2.8×1014sec-1 b) diethyleneglycoldiethylether-water system l=2.3Å β=1.6×1017sec-1 c) acetonitrile-water system l=2.8Åβ=6.5×1015sec-1 Finally, the difference in the values of the two parameters (l and β) among the three systems are discussed.
In the measurement of the two-dimensional autocorrelation, an optical, matched filtering is greatly being used where the processing has only been conducted under the condition of com-pletely coherent illumination. The present paper is undertaken to investigate the effect of spatial coherence on the matched filtering process. A generalized formula for the matched filtering under partially coherent illumination is obtained. The output intensities were then calculated for some special cases, in which the illuminating light in recording or filtering process is completely coherent. To verify the theory some experiments were carried out.
There are two ways of quantitative analysis is EPMA to obtain an average counting rate; counting for a fixed time and counting pulses for a fixed charge. The method of counting pulses for a fixed charge which is the more general one, is not suitable for quantitative measurements on specimens having a heterogeneous structure be-cause the specimen current varies in different regions of the structure. This paper initially presents an adaptor con-verting the device for counting pulses for a fixed charge into that of counting for a fixed time, and then shows by some experiments that the adaptor is also useful for quantitative analysis in EPMA.