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At a soft X-ray beamline with an undulator source, significant heat generation at the first-mirror chamber and light emission at the viewport were found, which can be explained by photoelectrons from the mirror. The chamber temperature increases up to approximately 50°C over a period of several hours. A photoelectron shield consisting of thin copper plates not only prevents the heat generation and light emission but also improves the pressure of the vacuum chamber, if a voltage of a few tens of V is applied to the shield. The total electron yield of the shield reached as much as 58 mA under high heat-load conditions, indicating the emission of numerous photoelectrons from the first mirror. Heat-balance analyses suggest that approximately 30% or more of the heat load on the first mirror is transferred to the surroundings.

Carbon contamination of a chromium-coated mirror was removed by exposure to oxygen activated with non-monochromated synchrotron radiation. Higher-order harmonics of the chromium-coated mirror are much smaller than those of a gold-coated mirror in the carbon K-edge region., Carbon-free chromium-coated optics are ideal in the carbon K-edge region (280–330 eV) because the reflectivity of first-order light is larger than that of gold-coated optics while the second-order harmonics (560–660 eV) are significantly suppressed by chromium L-edge and oxygen K-edge absorption. Here, chromium-, gold- and nickel-coated mirrors have been adopted in the vacuum ultraviolet and soft X-ray branch beamline BL-13B at the Photon Factory in Tsukuba, Japan. Carbon contamination on the chromium-coated mirror was almost completely removed by exposure to oxygen at a pressure of 8 × 10−2 Pa for 1 h under irradiation of non-monochromated synchrotron radiation. The pressure in the chamber recovered to the order of 10−7 Pa within a few hours. The reflectivity of the chromium-coated mirror of the second-order harmonics in the carbon K-edge region (560–660 eV) was found to be a factor of 0.1–0.48 smaller than that of the gold-coated mirror.

The undulator beamline BL-2C was constructed for measurements of soft X-ray spectroscopy. It is equipped with a varied line-space plane grating monochromator. High energy-resolution, high photon-flux and tiny spot-size have contributed to research on electronic structure of gaseous samples, solid samples and surfaces. In order to carry out further sophisticated measurement, we have improved the beamline at the following three points. First, optical elements were re-aligned again with great care for higher energy-resolution. To demonstrate the energy-resolution, we measured absorption spectrum of oxygen 1 s σ → π * excitation and evaluated E/ Δ E to be more than 10,000. Secondly, mirror holders were altered to reduce the effect of heat load. The remodeling and the replacement of the optical-element holders resulted in energy-drift becoming negligible. Thirdly, the carbon-contaminated optical elements were cleaned by ozone-cleaning method. The photon flux at the carbon absorption-edge is recovered by the cleaning.

Carbon contamination of optics is a serious issue in all soft X-ray beamlines because it decreases the quality of experimental data, such as near-edge X-ray absorption fine structure, resonant photoemission and resonant soft X-ray emission spectra in the carbon K-edge region. Here an in situ method involving the use of oxygen activated by zeroth-order synchrotron radiation was used to clean the optics in a vacuum ultraviolet and soft X-ray undulator beamline, BL-13A at the Photon Factory in Tsukuba, Japan. The carbon contamination of the optics was removed by exposing them to oxygen at a pressure of 10(-1)-10(-4) Pa for 17-20 h and simultaneously irradiating them with zeroth-order synchrotron radiation. After the cleaning, the decrease in the photon intensity in the carbon K-edge region reduced to 2-5%. The base pressure of the beamline recovered to 10(-7)-10(-8) Pa in one day without baking. The beamline can be used without additional commissioning.

The design and commissioning of a new soft X‐ray beamline, BL‐16A, at the Photon Factory is presented. The beamline consists of a pre‐focusing mirror, an entrance slit, a variable‐included‐angle varied‐line‐spacing plane grating monochromator, and a post‐focusing system as usual, and provides circularly and linearly polarized soft X rays in the energy range 200–1500 eV with an APPLE‐II type undulator. The commissioning procedure for the beamline optics is described in detail, especially the check of the focal position for the zero‐th order and diffracted X rays.

A planar undulator beamline, BL‐13A, covering 30–1,000 eV has been constructed in the Photon Factory. The main scientific targets are investigations of organic thin films and biomolecules adsorbed on well‐defined surfaces using angle‐resolved photoelectron spectroscopy, X‐ray photoelectron spectroscopy, and X‐ray absorption spectroscopy. A variable‐included‐angle Monk‐Gillieson mounting monochromator with varied‐line‐spacing plane gratings is used to achieve a high photon flux of 1010–1012 photons/s with a high resolution (E/ΔE) of 7,000–30,000. A typical spot size on the sample position is estimated to be 130 μm (horizontal)×40 μm (vertical). After commissioning, BL‐13A will be open for users from January 2010.

The design and performance of a 24 m high-resolution spherical grating monochromator (H-SGM) for the undulator beamline (BL-16B) at the Photon Factory are described. With three interchangeable gratings of 400, 900 and 2000 lines mm−1, the H-SGM is designed to cover the photon energy range 40–600 eV. With a resolving power of approximately 2000 in the photon energy range 40–530 eV, more than 1011 photons s−1 have been measured. The best resolutions obtained so far, at a substantially lower photon flux, are greater than 10 000 at 250 eV and 8000 at 400 eV

A new grazing incidence soft x-ray monochromator has been commissioned on the undulator beamline BL-2 of the Photon Factory. The monochromator has been designed to meet the demands for high-resolution soft x-ray spectroscopy. The monochromator has employed a varied space plane grating and a configuration with sagittal focusing and converging beam to satisfy the requirement. According to analytical estimation and ray tracing simulation, the high resolving power beyond 10000 can be obtained over the full energy range from 250 to 1400 eV. Preliminary experiments have been done on three points concerning the resolving power, photon flux, and spot size. The results have showed the typical resolving power from 7500 to 10000, the absolute photon flux ofthe order of lOb photons/s/300mA/O.02%BW, and the spot size ofO.1(V) x 0.9(11) 2FW at the sample position.

The design and performance of a new soft X-ray beamline BL-11A at the Photon Factory (PF) are presented. A Hettrick-type grazing-incidence monochromator equipped with three varied-line-spacing plane gratings was designed and constructed at a bending-magnet source of the PF 2.5 GeV storage ring. An 800 lines mm−1 laminar grating produced by aspheric-wavefront holographic recording optics, as well as a mechanically ruled blazed one, were tested. A resolving power of more than 4500 was achieved at 400 eV with either grating, and ∼1010 photons s−1 are available at a resolving power of 2000. High photon flux enables low-concentration samples, such as surface adsorbates, to be studied. A simple scanning mechanism for a wide energy range is quite useful for EXAFS measurements on light elements such as C, N and O.