Performance of BL07A at NewSUBARU with installation of a new multi-layered-mirror monochromator

Abstract

Soft X-rays excite the inner shells of materials more efficiently than any other form of light. The investigation of synchrotron radiation (SR) processes using inner-shell excitation requires the beamline to supply a single-color and high-photon-flux light in the soft X-ray region. A new integrated computing multi-layered-mirror (MLM) monochromator was installed at beamline 07A (BL07A) of NewSUBARU, which has a 3 m undulator as a light source for irradiation experiments with high-photon-flux monochromatic light. The MLM monochromator has a high reflectivity index in the soft X-ray region; it eliminates unnecessary harmonic light from the undulator and lowers the temperature of the irradiated sample surfaces. The monochromator can be operated in a high vacuum, and three different mirror pairs are available for different experimental energy ranges; they can be exchanged without exposing the monochromator to the atmosphere. Measurements of the photon current of a photodiode on the sample stage indicated that the photon flux of the monochromatic beam was more than 1014 photons s−1 cm−2 in the energy range 80–400 eV and 1013 photons s−1 cm−2 in the energy range 400–800 eV. Thus, BL07A is capable of performing SR-stimulated process experiments.

Photon energy dependence of graphene oxide reduction by soft X-ray irradiation and atomic hydrogen annealing

“…Under a storage ring current of 350 mA, the photon flux densities were 5.0 × 10 12 and 1.0 × 10 8 photons mm −2 s −1 at 300 and 550 eV, respectively. 31) The difference in GO reduction between 300 and 550 eV cannot be explained by the photon flux density because the photon flux density at 550 eV was lower than that at 300 eV. The actual absorbed soft X-ray level was estimated with the X-ray absorption and the photon flux density.…”