Deployments of spherical grids to obtain high energy and angular resolutions for retarding field analyzers (RFAs) having acceptance angles as large as or larger than ±45° were explored under the condition of using commercially available microchannel plates with effective diameters of approximately 100 mm. As a result of electron trajectory simulations, a deployment of three spherical grids with significantly different grid separations instead of conventional equidistant separations showed an energy resolving power (E/ΔE) of 3200 and an angular resolution of 0.6°. The mesh number of the wire mesh retarding grid used for the simulation was 250. An RFA constructed with the simulated design experimentally showed an E/ΔE of 1100 and an angular resolution of 1°. Using the RFA and synchrotron radiation of 900 eV, photoelectron diffraction (PED) measurements were performed for single-crystal graphite. A clear C 1s PED pattern was observed even when the differential energy of the RFA was set at 0.5 eV. Further improvement of the energy resolution was theoretically examined under the assumption of utilizing a retarding grid fabricated by making a large number of radially directed cylindrical holes through a partial spherical shell instead of using a wire mesh retarding grid. An E/ΔE of 14 500 was predicted for a hole design with a diameter of 60 μm and a depth of 100 μm. A retarding grid with this hole design and a holed area corresponding to an acceptance angle of ±7° was fabricated. An RFA constructed with this retarding grid experimentally showed an E/ΔE of 1800. Possible reasons for the experimental E/ΔE lower than the theoretical values are discussed.

We investigated the electronic and local crystal structures of the sintered half-Heusler ZrNiSn alloy by synchrotron radiation photoemission spectroscopy (SR-PES), synchrotron radiation X-ray powder diffraction (SR-XRD) measurements, and electronic band structure calculations to clarify mechanisms leading to improvements in the thermoelectric properties of materials. In contrast to the predicted semiconductor-like electronic structure, the SR-PES results show a pseudo-gap at the Fermi level, and the SR-XRD analysis reveals an interstitial Ni disorder in the half-Heusler structure. An improvement in the thermoelectric properties can be achieved by material design based on the pseudo-gap electronic structure of half-Heusler ZrNiSn-based alloys.

We use core level and valence band soft x-ray photoemission spectroscopy (SXPES) to investigate electronic structure of new BiS$_{2}$ layered superconductor LaO$_{1-x}$F$_{x}$BiS$_{2}$. Core level spectra of doped samples show a new spectral feature at the lower binding energy side of the Bi 4${f}$ main peak, which may be explained by core-hole screening with metallic states near the Fermi level ($E_{\rm F}$). Experimental electronic structure and its ${x}$ dependence (higher binding energy shift of the valence band as well as appearance of new states near $E_{\rm F}$ having dominant Bi 6${p}$ character) were found to be consistent with the predictions of band structure calculations in general. Noticeable deviation of the spectral shape of the states near $E_{\rm F}$ from that of calculations might give insight into the interesting physical properties. These results provide first experimental electronic structure of the new BiS$_{2}$ layered superconductors.Comment: 14 pages, 4 figure

We report the global structural alterations in histone H3 proteins induced by lysine-9 mono-, di- and trimethylation, which are part of the critical post-translational modifications for DNA damage responses, identified using synchrotron radiation circular dichroism (CD) spectroscopy. Compared with unmodified H3, mono- and dimethylation increases the number of α-helices and decreases the numbers of β-strands, while trimethylation decreases the α-helix content and increases the β-strand content. Comparison of the secondary-structure contents of these histone H3 proteins suggests that the methylation-induced structural alterations occur at residues not only close to but also distant from the methylated sites. Such global structural alterations may regulate the interactions of methylated histones with other molecules, such as histone-binding proteins in DNA damage repair processes.

Circular dichroism (CD) spectroscopy in the soft x-ray energy region is a new tool to study the local structure of chiral materials. In this paper, we introduce a method to measure high-quality CD spectra in the oxygen K-edge energy region. Characteristic CD spectra of thin films of the amino acids L-tyrosine and L-aspartic acid are reported and compared with those of films of L-alanine and L-serine. The signals from the oxygen 1s → π* transitions of COO⁻, which is a common moiety in these amino acids, reflect the local geometry of each amino acid.