Photoelectric Polarization Research Articles

基于水面特征波纹的潜艇多波段光电偏振成像探测性仿真研究

基于水面特征波纹的潜艇多波段光电偏振成像探测性仿真研究

Photoelectric response of localized states in silica glass

The photoelectric response of pure silica glasses excited by excimer lasers has been studied. The samples were made under various conditions. Photoelectric polarization of samples due to the Dember effect has been registered. The signal was recorded under the conditions of a space charge limited current. The space charge resulting from the capture of electrons and holes creates a static electric field that prevents diffusion of released charge carriers. The current registration in the external circuit stops, despite the continuation of photoexcitation. This effect was used as a fact of measuring the photocurrent in the sample volume instead of the parasitic current that is not associated with the sample. The screen has been chosen to prevent the influence of a spurious signal. It has been found that charge carriers are released when excited in the spectral absorption range of localized states of silica. Based on the Dember effect, the sign of the photoelectric response shows the type of charge carriers - an electron or a hole is mobile. Thus, a sample containing aluminum without alkali ions gives a negative signal, which indicates the diffusion of electrons at 290 K, since aluminum is an effective hole trap. An oxygen-deficient sample at 290 K provides a positive signal indicating the diffusion of holes, because the center of oxygen deficiency is an effective electron trap. This sample at 100 K provides a negative signal due to the effective self-trapping of holes.

Formation of nanoporous anodic films on pure aluminum in sulfuric acid

The effect of the duration of electrochemical anodic oxidation on the formation of nanoporous anodic oxide films on high-purity aluminum (99.99%) in a sulfuric acid solution is studied. The resulting oxide film is analyzed using an atomic force microscope. The method of photoelectric polarization (PEP) and X-ray analysis revealed that these films are sesquioxides of aluminum with variable compositions, nonstoichiometry due to a metal deficiency, and p-type conductivity. The mechanism of the formation of a regular nanoporous oxide structure that results from the nonstoichiometry relation and the intrinsic formation of defects in the oxide is proposed.

Phase transitions of liquid crystalline cyanoethyl cellulose solutions under static conditions and in shear field

Phase transitions in the systems cyanoethyl cellulose-DMF, cyanoethyl cellulose-DMAA, and cyanoethyl cellulose-(trifluoroacetic acid + methylene chloride) were studied by means of the cloud-point and polarization microscopy techniques, as well as with a photoelectric polarization unit and a modified plasticorder. It was shown that the LC phase appears at higher concentrations and lower temperatures as the polarity of solvent molecules increases. The shear deformation of cyanoethyl cellulose solutions in DMF and DMAA results in the expansion of the temperature-concentration region of existence of the LC phase. The effect of shear field on phase transitions in cyanoethyl cellulose solutions is nonmonotonic in character.

窒化チタンの半導体特性とアノード溶解反応

Titanium nitrides were prepared by high-temperature nitriding and reactive ion plating, and their semiconducting properties were studied by photoelectric polarization. All the nitrides prepared by nitriding showed negative photopotential, which means that they exhibited n-type conduction. The magnitude of the photopotential, however, varied depending on the nitriding temperature, form -10-5∼-10-4V at 773∼873K to about -10-7V at 973∼1473K, and the properties of TiN (N=47.12at%) prepared by reactive ion plating were similar to those of the latter. Subsequently, the dissolution reaction of titanium nitride in sulfuric acid solution was inferred from the semiconducting properties and valency, which could be calculated from the quantity of electricity and the amount of titanium dissolved during potentiostatic polarization. The lower nitride Ti2 N dissolved according to the process Ti2N+4H+=2Ti3++NH4++3e-, whereas with the higher nitride TiN the reaction was assumed to involve Ti+. Light irradiation of the surfaces of the both nitrides generated a reaction involving positive holes.

Cuの高温酸化皮膜の光電気化学的挙動

The photopotential vs. time curves and photoelectric polarization curves of copper oxide films formed by high temperature oxidation were measured in Na2SO4 solutions of various pHs. Particular attention was given to the difference in these curves between CuO(outer)/Cu2O(inner) film and Cu2O single film. The signs of photopotentials for the CuO/Cu2O films were independent of solution pH, and were positive. On the contrary, those of the Cu2O film varied, depending on the pH region of the solution, that is, the signs observed in the solutions at pH2∼5 were positive, whereas those at pH5∼12 were negative. A relatively large photocurrent of the CuO/Cu2O film was observed as a cathodic current, while the anodic photocurrent of the film was hardly observable. In contrast, both anodic and cathodic photocurrents were observed for the Cu2O film. It was found that in the solutions of pH2∼12, flat-band potentials of the CuO/Cu2O films were higher than those of the Cu2O films. It was observed for both oxide films that the relative height between the flat-band potential and the rest potential determines the sign of photopotential. Such a difference in photoelectrochemical behavior between the two films was explained in terms of the energy-band model in the vicinity of the oxide surface.

Fe-Cr合金の不働態皮膜の半導体的性質の光電分極法による解析

Fe-Cr合金の不働態皮膜の半導体的性質の光電分極法による解析

Electrochemical behaviour of the oxide covered antimony

The electrochemical behaviour of the system Sb-oxide layer-0.05 M H 2SO 4 was investigated by impedance, photopolarization and by recording voltammetric characteristics in the presence of the redox couple K 3Fe(CN) 6-K 4Fe(CN) 6 from 1.6 to −0.86 V vs mercury mercurous sulphate electrode. Attention has been concentrated on potentiodynamically formed and stabilized films whose thickness enabled the development of the space charge. It will be shown that the mechanism of charge transfer in the Sb-oxide layer-electrolyte system having a given form of current potential characteristics, is dependent on the semiconducting properties of the oxide layer, which can be modified owing to the breaking of bonds and the formation of new ones. Impedance and photoelectric polarization have proved very sensitive and suitable for the investigation of structural and phase change of the solid phase in situ with potential changes in continuous polarization.

Imaging polarimetry of the jets of M87 and 3C 273

Photoelectric polarization maps of the jets associated with M87 and 3C 273 are presented. For the M87 jet, polarization of individual knots reaches 20%. Comparison of the complex position angle structures at optical and radio frequencies (i) indicates the presence of a uniform (scale length> or approx. =1.5 kpc) medium in the vicinity of M87 which causes a Faraday rotation along the line of sight greater than approx.360rad m/sup -2/, and (ii) places an upper limit on the amount of Faraday depolarization occurring within individual knots.For the 3C 273 jet as a whole, our observations yield P=3.7% +- 4.1%. This measurement is consistent with inverse Compton models of the optical emission; however, a synchrotron origin cannot be excluded if the small-scale structure of the 3C 273 jet is similar to that of the jet of M87.

Photoelectric polarization maps of two bipolar reflection nebulae

view Abstract Citations (55) References (31) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Photoelectric polarization maps of two bipolar reflection nebulae. Schmidt, G. D. ; Angel, J. R. P. ; Beaver, E. A. Abstract A rapidly chopping polarimeter equipped with a large-aperture Pockels cell and 200-element digicon detector was used to obtain high-resolution maps of the optical polarization and surface brightness in the bipolar nebulae CRL 2688 and M 1-92. Both nebulae show radially symmetric polarization patterns characteristic of reflection and, except for the northwest lobe of M 1-92, are apparently optically thin to scattering. The very high polarization in CRL 2688 indicates small scattering grains, and the stellar spectrum is substantially blued upon reflection. Values of a color excess produced by circumstellar and interstellar extinction and of the visual extinction along the optical path of a scattered photon are estimated. The existence of small grains, optical thinness, and symmetric geometry indicates that scattering by or transmission through a medium of aligned grains is responsible for the circular polarization observed in CRL 2688. One possibility is that alignment by an interstellar magnetic field at an angle to the axis of the nebula provides the necessary skew geometry. Publication: The Astrophysical Journal Pub Date: January 1978 DOI: 10.1086/155803 Bibcode: 1978ApJ...219..477S Keywords: Astronomical Maps; Linear Polarization; Nebulae; Polarization Characteristics; Interstellar Magnetic Fields; Interstellar Matter; Magnetic Effects; Planetary Nebulae; Astrophysics; Polarization:Reflection Nebulae full text sources ADS | data products SIMBAD (7)

Aerodynamic and optical properties of ice crystals

Optical and aerodynamic properties of ice crystals were investigated in a cold chamber. The following instruments were used: single-channel photometers for determining the extinction of visible and i.r. laser radiation, a scanning device for measuring the angular distribution of scattered radiation in the visible and i.r. bands, a photoelectric polarization device for measuring the concentration of crystal particles and a remote control sampler. Sedimentation velocities, thickness and orientation of crystals, the asymmetry in the scattering pattern in two orthogonal planes, the angular distribution of scattered radiation and coefficients of radiation extinction by crystal media were determined.

The polarization curve and the absolute diameter of Vesta

Abstract A new photoelectric polarization curve for Vesta is presented. It is incompatible with Lyot's photographic curve which appears to be inaccurate. The new polarization curve indicates that the reflectivity of Vesta is higher than that of the Moon, and a pre;iminary value of 0.25 ± 0.07 for the reflectivity in the V is suggested. This implies an absolute diameter of about 510 km, a value consistent with the diameter of Vesta calculated from its mass, assuming an achondritic composition.

Asteroid Polarimetry: A Progress Report

This is a brief report on the present status of asteroid polarimetry. A detailed paper is in preparation jointly with T. Gehrels.The first polarization measurements of asteroids were made by Lyot (1934), who photographically determined the polarization curves of Ceres and Vesta. These curves are reproduced by Dollfus (1961). Unfortunately, because of the low sensitivity of the photographic method, they do not agree very well with recent photoelectric measurements.The first photoelectric polarization measurements of asteroids were made by Provin (1955) (details of this work are given by Dollfus, 1961), and in recent years this work has been extended by Gehrels (unpublished) and by Veverka (1970). To date, fairly complete polarization curves for about a dozen asteroids have been obtained, and at least partial data are available for twice that number.

Photoelectric Measurements of Sunspot Magnetic Fields

Photoelectric polarization measurements in a stable sunspot (type H) with a particularly dark umbra, where ‘umbral dots’ were virtually lacking, have been carried out with the Capri magnetograph. The measurements were evaluated in terms of Unno's theory to give the value and direction of the magnetic field vector. The parameters η0 = 5, β0 = 2.5 and ΔλD = 40mÅ have been adopted for the Fe I 5250 line. Taking the configuration of the sunspot into account as well as simple conditions of steadiness of the distributions to be obtained, it is possible to derive the magnetic vector field from two-dimensional records of circular and linear polarization without ambiguities.

Calibration of a Photoelectric Polarization Photometer for Directional Variation of Response

Calibration of a Photoelectric Polarization Photometer for Directional Variation of Response

Photoelectric polarization of ZnS and CdS self-activated phosphors

Photoelectric polarization of ZnS and CdS self-activated phosphors

Longitudinal Magneto-Optic Effect in Ferromagnetic Thin Films. II

The longitudinal Kerr and Faraday effects in Ni and 80% Ni Permalloy films are investigated by the use of a photoelectric polarization spectrometer. The refractive indices and the gyroelectric constants of Ni or Permalloy films are chosen as 1.40 (1–1.80i) or 1.65 (1–1.70i) and 4.55×10-3 exp {i(21^°)} or 1.20×10-2 exp {i(26^°)}, respectively, at the wavelength of 550 mµ. Then the theoretical values of rotation as a function of the angle of incidence and the film thickness calculated from the equations given in I agree fairly well with the experimental results. The wavelength dispersion of the rotation and the boundary surface effect of these films are also treated.

Photoelectric Polarization and Color Measures of Hubble's Variable Nebula, NGC 2261.

Photoelectric Polarization and Color Measures of Hubble's Variable Nebula, NGC 2261.

Longitudinal Kerr Magneto-Optic Effect in Permalloy Film

The longitudinal Kerr effect in an evaporated film of nickel (80%) and iron (20%) alloy is investigated by the use of a photoelectric polarization spectrometer. The Kerr rotation of the film is measured as a function of the angle of incidence for several wavelengths of light ranging from 400 mµ to 650 mµ. The compensation of the phase angle of the rotation with which the reflected beam of elliptically polarized light degenerates into a linear polarized light is also made with a Babinet Soleil compensator. When the values of the magneto-optic quantity and the refractive index of the film are chosen as 1.48×10-2exp {i(32^°)} and 1.76(1-1.84i), respectively, at the wavelength 592 mµ, the calculated values of the rotation given by the theory of Voigt agree well with the experimental results.

Letters to the Editor Photoelectric Polarization Observations of the Jet in M87.

Letters to the Editor Photoelectric Polarization Observations of the Jet in M87.