Eiji Ishiguro

A plane-grating monochromator for 2 eV ≤ hv ≤ 150 eV

Abstract Design and performance of a plane-grating monochromator at UVSOR facility are described. Two monochromators of the present design have been constructed and are used for optical and photoelectron spectroscopy of solids.

Constant deviation monochromator for the range 100 Å≤λ≤1000 Å

A grazing incidence constant deviation monochromator with a spherical concave grating was fabricated for use with undulator radiation. It has a simple scanning mechanism with fixed entrance and exit slits, as well as fixed directions of incident and exit beams. It has been installed into an undulator beamline at IMS. Synchrotron radiation from a bending section also can be introduced into the monochromator by using premirrors. The energy resolution of the monochromator is better than 70 meV at the photon energy of 94 eV with 10‐μm slits, when the bending magnet synchrotron radiation is used. The spot size of the zeroth‐order light is 1.5(v)×2.0(h) mm2 at the distance of 1.85 m behind a postmirror. The photon flux of the undulator radiation behind the exit slit is approximately 1×1012 photons/s at the peak, when both the entrance and exit slits are 100 μm (ΔE=0.08 eV) and the stored current is 50 mA.

CONSTRUCTION OF CONSTANT-+DEVIATION CONSTANT-LENGTH SPHERICAL GRATING MONOCHROMATOR AT UVSOR

A constant‐deviation constant‐length spherical grating monochromator was constructed at the bending‐magnet beamline 8B1 of the UVSOR. The monochromator has a simple scanning mechanism with a fixed position of the entrance and exit slits, as well as fixed directions of incident and exit photon beams. The monochromator was designed to cover the photon energy of 31–620 eV with three interchangeable laminar gratings (1080 lines/mm: R=15 m, 540 lines/mm: R=15 m, 360 lines/mm: R=7.5 m). All gratings are original gratings fabricated on synthetic quartz substrates and coated with Au. The resolving power evaluated by ray tracing at the lowest energy of each grating with 10 μm slit width is ∼4400 for two high energy gratings and ∼7000 for a low energy grating. In the preliminary performance check, it was found that the output spectrum of the monochromator with G1 grating extends up to 870 eV with resolving power of ∼4000 at 400 eV with 10 μm slits.

Optical Spectra of Cadmium Halide Crystals in 3–30 eV Region

Reflection spectra of single crystals of CdCl 2 , CdBr 2 and CdI 2 at 35 K were measured in the region up to 30 eV using synchrotron radiation. Photoemission experiments were also performed on in-situ evaporated films of cadmium halides to determine binding energies of the outermost s -core levels of halogen ions. Optical constants were derived through Kramers-Kronig analysis. In the region up to 15 eV were found a number of peaks which are attributed to the transitions from the halogen valence band to the cadmium 5 s and 5 p conduction bands. Around 16 eV were observed the peaks due to the Cd 4 d core excitons. Weak structures in the 19-24 eV region are assigned to the transitions from the halogen s -core levels. In CdI 2 , it was found that the total oscillator strength for the transition from the valence band is enhanced due to the presence of shallow core levels.

A plane‐grating monochromator for radiometric calibration

A new plane‐grating monochromator and calibration chamber were constructed for the radiometric calibration of plasma diagnostic devices. The monochromator is designed to cover a wavelength range of 1.8–238 nm with moderate resolving power of 500±200 in λ/Δλ. To check the performance of the monochromator, spectral distribution and resolution were measured by experiments on photoemission from solids and photoionization of rare gases. The characterization of multilayer reflectors by the use of this beamline is demonstrated.

Monochromator for circularly polarized synchrotron radiation in the energy range of 5–250 eV

A new spherical grating monochromator with translational and rotational assembly including a normal incidence mount (SGM‐TRAIN) is under construction at BL 5A of the UVSOR Facility, IMS, and its design concept is reported. The following points have been taken into account in the design: (1) Energy range of 5–250 eV, (2) use both of undulator and bending magnet radiation, (3) linear and circular polarizations, (4) spectral purity, (5) resolution, and (6) length of beamline. It should be stressed that the SGM‐TRAIN is useful for experiments where circularly polarized synchrotron radiation is used. Moreover, the SGM‐TRAIN has the advantage that the small emittance of storage ring and the large space for a long beamline are not necessary.

Photovoltaic properties of azo compounds containing the thiazole group

Abstract Thiazole-containing azo compounds were synthesized and their photovoltaic properties investigated using a sandwich cell with Al and Ag electrodes. Rectification characteristics were observed in dark current and photocurrent for all compounds. The action spectrum of the photocurrent shows an antibatic correlation with the absorption spectrum for most of the compounds, except for two compounds which have a symbiotic correlation when illuminated through an Ag electrode. This difference between the action spectra is discussed in terms of the Hammett constants of the electron-donating group in the azo compounds and the oxygen molecules adsorbed on the surface. The effects of substituent groups on the photovoltaic output are also discussed.

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.

Fabrication and characterization of reactive ion beam etched SiC gratings

A holographic SiC grating has been fabricated by means of reactive ion beam etching in Ar+CHF3 mixture and by using photoresist as an etching mask. The etch rates of SiC and photoresist depend on the CHF3 concentration in Ar+CHF3 mixture. A maximum value for a ratio of the etch rate of SiC to that of photoresist was found to be 1.29 for 67%Ar+33%CHF3 mixture. Diffraction efficiency of an ion‐beam etched grating of 1200 l/mm grooves coated with Au was measured by using synchrotron radiation and the Al kα emission line from an x‐ray tube. The diffraction efficiency of the first order was 4.5%–9.3% in the soft x‐ray region between 8.34 and 120 A with a small amount of the higher order and the scattered light components. In addition, it is demonstrated that SiC can be etched in SF6 gas by synchrotron radiation excitation.

The UVSOR facility at IMS

The construction of a synchrotron radiation facility, dedicated to VUV studies in molecular science and its related fields, has started this year at the Institute for Molecular Science, Okazaki, Japan [1]. The facility consists of a 600 MeV storage ring, a 600 MeV injector synchrotron with a 15 MeV linac, experimental stations, and several experimental support facilities in a 2700 m2 building. The storage ring has a circumference of 53.2 m, consisting of eight bending magnet sections, four short straight sections, and four long straight sections. The radius of the bending magnet is 2.2 m, making the use of radiation down to 10 A feasible at 600 MeV electron energy (λc = 56.9 A). The proposed researches include spectroscopy, phototelectron spectrocopy, photochemistry, and reaction dynamics of active species. Optical and other instruments for these studies have been designed and some have been constructed.