NW14A is a newly constructed undulator beamline for 100 ps time-resolved X-ray experiments at the Photon Factory Advanced Ring. This beamline was designed to conduct a wide variety of time-resolved X-ray measurements, such as time-resolved diffraction, scattering and X-ray absorption fine structure. Its versatility is allowed by various instruments, including two undulators, three diffractometers, two pulse laser systems and an X-ray chopper. The potential for the detection of structural changes on the 100 ps time scale at NW14A is demonstrated by two examples of photo-induced structural changes in an organic crystal and photodissociation in solution.

The magnetic states of Mn and Co atoms in Co-rich Co 2 MnGe Heusler alloy thin films facing an MgO barrier were studied by means of soft x-ray magnetic circular dichroism ͑XMCD͒. In particular, the Co 2 MnGe film-thickness dependence of the Mn and Co magnetic moments was investigated. With a decrease in the Co 2 MnGe film thickness to 1-2 monolayers ͑MLs͒, the spin magnetic moment of Mn decreased and the Mn L 2,3 -edge x-ray absorption spectra ͑XAS͒ showed a Mn 2+ -like multiplet structure in MnO, in contrast to samples thicker than 4 ML, indicating that the Mn atoms of the 1 and 2 ML samples were oxidized. The Co spin magnetic moment increased slightly with decreasing thickness. A Co 2+ -like multiplet structure in CoO was not observed in all the Co L 2,3 -edge XAS and XMCD, indicating that, even in the ultrathin samples, the Co atoms were not oxidized, and were more strongly spin polarized than those in the thicker samples. Co spin magnetic moments of 1.40-1.77 B larger than the theoretical value for ideal stoichiometric Co 2 MnGe ͑ϳ1 B ͒ and the Co-rich film composition imply the presence of Co antisites that would lower the spin polarization.

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