Showing papers by "University of Electro-Communications published in 1972"

Reflectivity of Metals at High Temperatures

Abstract: The reflectivity and other optical constants of metals at high temperatures are discussed on the basis of the Drude theory and the theory of electron‐phonon collision. The electron‐phonon collision frequency is dependent on the temperature through the temperature dependence of the phonon population. The temperature dependence of the collision frequency determines that of optical properties of metals. Variations of the real and the imaginary parts of the dielectric constant and of the complex refractive index with temperature are considered. General expressions for the temperature coefficients of the optical constants are given. The reflectivity is shown to decrease with increasing temperature. Numerical calculations were carried out for several metals at a few wavelengths and at temperatures from room temperature to their melting temperatures. The results are given in graphs and in a table. Curves for the reflectivity show that the absolute value of the temperature coefficient of the reflectivity is greater for a metal having a lower reflectivity at room temperature. Calculated values of the reflectivity at room temperature are in reasonable agreement with handbook data. However, the calculated reflectivity for silver at its melting point is not coincident with the reported experimental data (the only data available at present), in spite of the qualitative agreement between our results and the experiment. A brief discussion on possible explanations of the discrepancy is made.

Reflectivity of metals at high temperatures

Abstract: The reflectivity and other optical constants of metals at high temperatures are discussed on the basis of the Drude theory and the theory of electron‐phonon collision. The electron‐phonon collision frequency is dependent on the temperature through the temperature dependence of the phonon population. The temperature dependence of the collision frequency determines that of optical properties of metals. Variations of the real and the imaginary parts of the dielectric constant and of the complex refractive index with temperature are considered. General expressions for the temperature coefficients of the optical constants are given. The reflectivity is shown to decrease with increasing temperature. Numerical calculations were carried out for several metals at a few wavelengths and at temperatures from room temperature to their melting temperatures. The results are given in graphs and in a table. Curves for the reflectivity show that the absolute value of the temperature coefficient of the reflectivity is greater for a metal having a lower reflectivity at room temperature. Calculated values of the reflectivity at room temperature are in reasonable agreement with handbook data. However, the calculated reflectivity for silver at its melting point is not coincident with the reported experimental data (the only data available at present), in spite of the qualitative agreement between our results and the experiment. A brief discussion on possible explanations of the discrepancy is made.

Electron Transfer from Highly Excited Atoms to Molecules

Abstract: It is theoretically shown that the rate constant for reaction of electron transfer from highly excited atoms A ** to polyatomic molecules B, \begin{aligned} \text{A$^{**}$}+\text{B}{\rightarrow}\text{A$^{+}$}+\text{B$^{-}$}, (1) \end{aligned} at thermal velocities is equal to that of non-dissociative thermal electron capture by the molecules B, \begin{aligned} \mathrm{e}+\text{B}{\rightarrow}\text{B$^{-}$}, (2) \end{aligned} based on the assumption that the negative ion formed in reaction (1) is the same species as that formed in reaction (2). The result obtained is in reasonable agreement with experimental data for reaction (1) between Ar and SF 6 . From both the present study of reaction (1) and the previous work on the ionization of the highly excited atoms by collision with polar molecules (M. Matsuzawa; J. chem. Phys. 55 (1971) 2685), it can be concluded that knowledge of inelastic scattering of a slow electron by molecules is very useful for the understanding of some kind of reactions of the highly ...

Heitler-London Calculation on the Bonding of Oxygen to Hemoglobin. : I. Singlet States in the Case of O-O Axis Parallel to Heme Plane

Abstract: Bonding of O 2 to heme is studied by Heitler-London calculation with three ionic structures (Fe 2+ –O 2 , Fe 3+ –O 2 - and Fe + –O 2 + ). The basic configurations are constructed from the low-lying terms of Fe 2+ , Fe 3+ and Fe + in the heme, and those of O 2 , O 2 - and O 2 + . Hamiltonian matrix elements are evaluated with the method of “Atoms in Molecule.” The empirically determined term energies of O 2 are used and the electronic structure of Fe atom in the heme is estimated with the ligand field theory. The molecular integrals necessary for the evaluation of interaction part are computed with the Gaussian type SCF atomic orbitals. As O 2 approaches to the heme, one of the 1 A 2 states, which is the combination of the excited 3 E term of the heme and the ground 3 Σ g - term of O 2 , becomes the ground state. In this state the negative exchange interaction between O 2 and Fe atom is effective in lowering the energy.

Evaluation of molecular spin-orbit integrals by a gaussian expansion method

Abstract: A method is presented for the evaluation of molecular multi-centre spin-orbit integrals of Coulomb, hybrid and exchange types using cartesian gaussian functions. It is shown that if gaussian bases are employed the spin-same-orbit integrals reduce to one-electron field integrals and the spin-other-orbit integrals to two-electron field integrals. The final formulae for these integrals are found to be convenient for computer programming. Some relationships among the nuclear attraction, the field and the field-gradient integrals as well as among the electronic repulsion, the two-electron field, and the zero-field splitting integrals are discussed in connection with the spin-orbit integrals. Some calculations are carried out for the radicals CH2 and NH.

Ferromagnetic Resonance in Thin Films of the System MnSb-CrSb

Abstract: A study is made on magnetic properties of thin films of Mn 1- x Cr x Sb(0≦ x ≦0.6) through ferromagnetic resonance. The films are deposited on plates of cover glass or rock salt to be 400 A to 3000 A in thickness. The spin wave resonance is observable at room temperature only when x ≤0.5. All the values of exchange coupling constant A , g -factor g and stress field 3λσ/ M decrease with the increase of x . Dependence of g and A on x are reasonably explicable on the basis of a canted spin structure where the spin axis lying within a ferromagnetic (001) layer is canted with that in the adjacent layers.

A Method of Testing the Effectiveness of a Protective Coating Layer on any Glass Surface against Alkali Vapours

Abstract: Publisher Summary This chapter discusses a possibility of testing the effectiveness of a protective layer coated on a glass surface against alkali vapors in general, and cesium (Cs) vapor in particular, by the use of short-circuit current characteristics. The material to be used for protecting the surface of any glass bulb against Cs vapor should not be reduced by Cs. It is also desirable that the layer should have a high electrical resistivity. Of various possible materials, oxides were thought to be most convenient to try. Whether an oxide may be reduced by Cs can be predicted by calculations based on free-energy data. Corning 0083 and 0089 glasses were used specifically in the experiment. Besides these, ordinary commercially available soda-lime glass and fused silica were also used in some cases. From the experimental results obtained, it may be concluded that the proposed method of testing is very sensitive and useful for practical purposes, and that the deposited layer of silica is more or less effective in prolonging the tube life regarding Cs absorption at temperatures lower than about 200 ° C , but it is not yet an ideal technique.

Effect of Optical Pulse Height Distribution on the Resolving Power of an Image Tube

Abstract: Publisher Summary This chapter examines the effect of optical pulse height distribution on the resolving power of an image tube In image tubes and television camera systems, the optical signal-to-noise ratio of the output image is of importance The noise generated at the input of the tube that includes input photon noise, as well as the signal, is decreased by virtue of the filtering action of the modulation transfer function A theoretical study is made of the signal-to-noise ratio of the output image of a high-gain image tube when a weakly illuminated black-and-white bar pattern is projected as the input image The two-dimensional signals of an object, input and output image in a summation time are shown The projection of a black-and-white bar pattern of line number, on to the photocathode corresponds to the on–off operation of a switch A multistage image tube is used as the spatial low-pass filter in the experiments so that the experimental results are applicable to the other high-gain image-intensifying systems such as low light-level camera tubes and X-ray television

Multiple Kink Effect in Graphite

Abstract: It is found that the current-voltage relation of graphite has three kink points under the influence of a transverse magnetic field at 77 K and 300 K. This phenomenon, in spite of its appearance at these high temperature, is identified as Esaki effect, and three kinks are attributed to the interaction between carrier particles and three modes of phonons. In graphite carriers interact with the transverse mode as well as the longitudinal one unlike in an ordinary non-polar material. A theoretical analysis yields an information on the number of the carriers contributing to each mode.

Construction of an Ion Cyclotron Resonance Mass Spectrometer

Abstract: Construction of an ion cyclotron mass spectrometer is reported. The apparatus has been built with electromagnet and analyzer cell Varian Associates and is similar to that described by Beauchamp, Anders and Baldeschwieler. Details of the spectrometer are described. The theory of ionci motion in the analyzer cell is presented in order to compare with performance of the spectrometer. The instrument is sensitive to as few as ten ions in the analyzer cell and a resolution has been found to be about 1, 100 at m/e 84 with the resonance frequency of 153 kHz. Half-width at half maximun of the collision-broadened absorptin line of N2+ in their parent gas has been measured as a function of pressure and the collision cross section and ion mobility of N2+ have been calculated as 210±30A 2 and 1.83±0.30 cm2/V·sec, respectively.

Variational Calculation of the Asymptotic Values of Quantum Defect for Helium

Abstract: For 1 S and 3 S Rydberg series of helium, it is successfully attempted to improve Smith's Hartree-Fock type variational calculation of the asymptotic values of quantum defect, Δ ∞ , by adding only a few configurational wavefunctions of analytic form to the primary Hartree-Fock type one. The best values of non-linear parameters in the added configurational wavefunctions are chosen on the basis of the minimum principle for Δ ∞ , which is here rederived straightforwardly from a well-known theorem on Rayleigh-Ritz's variational treatment. The integer parts of Δ ∞ 's, that have been left indefinite in all the calculations by predecessors, are determined pure-theoretically with the help of another inequality relation which is also a direct consequence of the same theorem.