Takanori Oshio

Soft X-Ray Absorption Spectra of Metals and Alloys. I. Be, Al, Sb, Bi and Al-Mg Alloys

Soft X-ray absorption spectra of Be, Al, Sb and Bi, and Al-Mg alloys have been obtained by the use of synchrotron radiation emitted from the 750 MeV electron synchrotron at the Institute for Nuclear Study, Tokyo, as a continuous light source. The K-absorption structure of beryllium was found to agree with the density of states calculated by Loucks and Cutler. Some correspondence was found between the maxima in the L 2,3 -absorption spectrum and the K-absorption spectrum of aluminum. A remarkable band was observed in the L 2,3 -absorption spectrum of aluminum at 23 eV above the edge. This band is not attributable to the singularity in the state density of the conduction band. A tentative interpretation based on the delayed onset of transitions 2 p -∞ d is proposed. The L 2,3 -absorption spectrum of aluminum in Al-Mg alloy shows a remarkable degeneration of the edge, while the L 2,3 -absorption edge of magnesium in the same alloy seems relatively unaffected. This behavior is similar to the effect reported b...

Cl− L23 absorption spectra of alkali chlorides obtained at 80°K with synchrotron radiation

Abstract Cl - L 23 absorption spectra of alkali chlorides have been obtained at 80°K with a 2 m grazing incidence spectrograph. Synchrotron radiation emitted from a 1.3 GeV electron synchrotron at INS ∗ has been used as a continuum background. The experimental results are interpreted in terms of X-ray exciton, electronic band structure, and two electron excitation.

Geometric optical theory of diffraction gratings

The aberration theory of diffraction gratings has been studied by means of geometric optics. No restrictions are imposed on the form of the grating surface, the pattern of the grooves in the grating surface, and the position of the object. Furthermore, the image plane is not limited to one normal to the principal ray. All of the terms up to the fourth order with respect to the pupil coordinates are taken into account in a series expansion of the light path function. The results give the focal positions, the radius of curvature of the astigmatic image, the shape of this image, the optimum slant angles of the image plane, the resolution by geometric optics, and the condition for absence of comatic broadening.

Scanning tunneling microscopy/spectroscopy study of V2O5 surface with oxygen vacancies

The geometric and electronic structures of the V2O5(010) surface with oxygen vacancies were studied by means of scanning tunneling microscopy/spectroscopy. Vanadyl oxygens which play an important role in an oxidization catalyst are found to be easily desorbed in a line along the c axis by annealing the sample above 500 °C. We obtained the current images of vanadium V4+ ion rows caused by the desorption of vanadyl oxygens and also the images of V5+ ion rows distinctively. Periodic vanadium ion rows having about a half‐space of lattice constant a of V2O5 were observed when almost all vanadyl oxygens were desorbed from the surface.

Aberration reduced mechanically ruled grating for simple rotational mounting

The imaging properties of aspherical diffraction gratings that have curved and variable spacing grooves are studied theoretically for simple rotational mountings. Methods for eliminating aberrations are examined by clarifying the relations of both the shape of the grating surface and the pattern of the grooves to the individual aberrations, such as astigmatism, coma, and curvature. Application of the methods to the Seya-Namioka mounting shows (i) a spherical grating with straight grooves of variable spacing, designed for elimination of coma, can give very sharp images over a wide spectral range; and (ii) a torus grating with curved grooves of variable spacing can give stigmatic images without serious image broadening. Therefore, resolution can be much improved in both spherical and torus gratings compared with those having conventional (straight and constant spacing) grooves.

Compact Metal-Ion Beam Source Using Thermal Contact Ionizer

A small, compact ion beam source which can function in an external magnetic field has been developed for use with a heavy ion beam probe for plasma diagnostics. The source consists of a thermal contact ionizer with a beam material reservoir and an electrostatic lens system for beam acceleration and focusing. The beam can be modulated by means of a beam-extracting electrode. An alkali or an alkali earth metal ion beam was produced at energies up to 3 keV. The source functioned sufficiently well in a magnetic field up to 2 kG. The operating parameters for Cs+ and Ba+ ion beams were investigated in detail. A beam current up to 10 µA and a small diameter of 1 mm at the focusing point were obtained.

Atomic Force Microscope Using an Optical Fiber Heterodyne Interferometer Free from External Disturbances

This paper describes an atomic force microscope (AFM) using an optical fiber heterodyne interferometer free from external disturbances in the optical paths of two fibers used for measuring the small displacements of a cantilever. For the elimination of disturbances, the phases of beat signals for two points are differentiated. A special plano-convex lens with double optical axes is used for obtaining two beams at two points. The noise level of this interferometer is 4.5×10-3 nm/√Hz and is limited by the phase noise of the phase meter used. It is confirmed, by measuring the electric force between the tip and the sample, that the interferometer can be used for measuring the displacement of the cantilever. By inspecting the surface of an echellete grating, it is demonstrated that this AFM is a powerful tool for measurement of the surface on the nanometer order.

Multistage Photoionization Chamber with Different Electrode Distances for the Measurement of the Absolute Intensity in the Vacuum Ultraviolet

A multistage photoionization chamber with different electrode distances has been devised to measure absolute photon fluxes in the vacuum ultraviolet, and was proved useful especially in short wavelengths. The device consists of a four-stage electrode in which the average traveling distance of electrons is increased in steps towards the end of the chamber. By finding the plateaus, the ratio of the ton currents for any two successive stages can be used as a measure of the correct operation of the chamber. Even under the conditions where secondary ionization occurs, the absolute photon flux can be determined by extrapolating the ion current to the distance at which the secondary ionization vanishes. Hence, this method makes possible a direct estimate of the absolute photon flux by a single experimental run regardless of secondary ionization. Examples are given at 584A.

Lyman‐alpha detector with MgF2 window

Ion chambers having a polished MgF2 window and filled with nitric oxide gas have been developed for the measurements of absolute intensities of solar and geocoronal hydrogen Lyman‐α radiation. The area sensitivities of the detectors and the effects of moisture on the transmittances of MgF2 single crystals were measured and compared with those in the cleaved LiF cases. The results indicate that an ion chamber with a polished MgF2 window has a superior suitability for the reliable measurement in rocket and satellite experiments as well as in laboratory work.

STM observation of grating surfaces

Three dimensional topographic images of optical grating surfaces have been obtained by the use of an STM. The STM can measure the grating surfaces in detail in air without touching the surfaces. The shape of an STM image is deformed from that of the real surface in some respects due to the finite radius of curvature, R, of the pointed probe tip. Reference figures, each of which shows the resultant STM shape of the image corresponding to a real surface having a certain set of values of blaze angle, {theta}, and apex angle, {phi}, have been prepared. With the aid of these figures, the authors estimate, conversely, values of {theta} and {phi}, in addition to R of the tip used, from the STM image obtained. The possible ambiguities in the estimation are also discussed. Thus, {theta} and {phi} values of gratings with line densities of 1,200 {approximately} 18,000 line/mm have been measured with errors of less than 10%. This conducting method with the use of an STM and reference figures may be very effective in the inspection of surfaces fabricated by submicron machining in general.