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In order to utilize high-brilliance photon sources, such as X-ray free-electron lasers (XFELs), for advanced time-resolved photoelectron spectroscopy (TRPES), a single-shot CCD-based data acquisition system combined with a high-resolution hemispherical electron energy analyzer has been developed. The system's design enables it to be controlled by an external trigger signal for single-shot pump-probe-type TR-PES. The basic performance of the system is demonstrated with an offline test, followed by online core-level photoelectron and Auger electron spectroscopy in 'single-shot image', 'shot-to-shot image (image-to-image storage or block storage)' and 'shot-to-shot sweep' modes at soft X-ray undulator beamline BL17SU of SPring-8. In the offline test the typical repetition rate for image-to-image storage mode has been confirmed to be about 15 Hz using a conventional pulse-generator. The function for correcting the shot-to-shot intensity fluctuations of the exciting photon beam, an important requirement for the TR-PES experiments at FEL sources, has been successfully tested at BL17SU by measuring Au 4f photoelectrons with intentionally controlled photon flux. The system has also been applied to hard X-ray PES (HAXPES) in 'ordinary sweep' mode as well as shot-to-shot image mode at the 27 m-long undulator beamline BL19LXU of SPring-8 and also at the SACLA XFEL facility. The XFEL-induced Ti 1s core-level spectrum of La-doped SrTiO3 is reported as a function of incident power density. The Ti 1s core-level spectrum obtained at low power density is consistent with the spectrum obtained using the synchrotron source. At high power densities the Ti 1s core-level spectra show space-charge effects which are analysed using a known mean-field model for ultrafast electron packet propagation. The results successfully confirm the capability of the present data acquisition system for carrying out the core-level HAXPES studies of condensed matter induced by the XFEL. [ABSTRACT FROM AUTHOR]

Hexavalent iridium (IrVI) oxide is predicted to be more active and stable than any other iridium oxide for the oxygen evolution reaction in acid; however, its experimental realization remains challenging. In this work, we report the synthesis, characterization, and application of atomically dispersed IrVI oxide (IrVI-ado) for proton exchange membrane (PEM) water electrolysis. The IrVI-ado was synthesized by oxidatively substituting the ligands of potassium hexachloroiridate(IV) (K2IrCl6) with manganese oxide (MnO2). The mass-specific activity (1.7 × 105 amperes per gram of iridium) and turnover number (1.5 × 108) exceeded those of benchmark iridium oxides, and in situ x-ray analysis during PEM operations manifested the durability of IrVI at current densities up to 2.3 amperes per square centimeter. The high activity and stability of IrVI-ado showcase its promise as an anode material for PEM electrolysis. [ABSTRACT FROM AUTHOR]

An insertion device capable of switching the operation mode between helical and figure-8 undulators, and thus referred to as a helical-8 undulator, has been developed. It has the advantage that the on-axis heat load can be kept low regardless of the polarization state, even when a high K value is required to lower the fundamental photon energy. This is in contrast to conventional undulators in which the on-axis heat load tends to be significantly high to generate linearly polarized radiation with a high K value, and optical elements can be seriously damaged. The principle of operation, specification and light source performance of the developed helical-8 undulator are presented together with further options to enhance its capability. [ABSTRACT FROM AUTHOR]

The streaming potentials of liquid beams of aqueous NaCl, NaBr, and NaI solutions are measured using soft X-ray, He(I), and laser multiphoton ionization photoelectron spectroscopy. Gaseous molecules are ionized in the vicinity of liquid beams and the photoelectron energy shifts are measured as a function of the distance between the ionization point and the liquid beam. The streaming potentials change their polarity with concentration of electrolytes, from which the singular points of concentration eliminating the streaming potentials are determined. The streaming currents measured in air also vanish at these concentrations. The electron binding energies of liquid water and I-, Br-, and Cl- anions are revisited and determined more accurately than in previous studies. [ABSTRACT FROM AUTHOR]