The design, construction and commissioning of a beamline and spectrometer for inelastic soft X-ray scattering at high resolution in a highly efficient system are presented. Based on the energy-compensation principle of grating dispersion, the design of the monochromator-spectrometer system greatly enhances the efficiency of measurement of inelastic soft X-rays scattering. Comprising two bendable gratings, the set-up effectively diminishes the defocus and coma aberrations. At commissioning, this system showed results of spin-flip, d-d and charge-transfer excitations of NiO. These results are consistent with published results but exhibit improved spectral resolution and increased efficiency of measurement. The best energy resolution of the set-up in terms of full width at half-maximum is 108 meV at an incident photon energy tuned about the Ni L3-edge.

In this work, we add a small amount of a guest-host dye G-206 in the polymer-dispersed liquid crystal mixtures to fabricate holographic gratings. Following formation, the grating is irradiated by a single Ar ϩ laser beam while probed by a He-Ne laser. Experimental results indicate that the first-order diffracted intensity of the probe beam increases significantly. Such an optically switchable diffraction effect is attributed to thermal expansion. The G-206 dye absorbs the Ar ϩ laser, subsequently resulting in thermal expansion. The liquid crystal ͑LC͒ droplets are then squeezed so that the LC molecules within the droplets are reoriented collectively. Thus, the refractive index difference between the LC-rich and polymer-rich stripes ⌬n increases.

for their helpful comments on an earlier version of this article. We also thank Haiyi Liu, Ko Nai Chi, and Xin Huang for their help in collecting the data for this work.

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A synchrotron-radiation-based circular-dichroism end-station has been implemented at beamline BL04B at the National Synchrotron Radiation Research Center (NSRRC) in Taiwan for biological research. The design and performance of this compact end-station for measuring circular-dichroism spectra in the vacuum-ultraviolet region are described. The linearly polarized light from the beamline is converted to modulated circularly polarized light with a LiF photoelastic modulator to provide a usable wavelength region of 130-330 nm. The light spot at the sample position is 5 mm × 5 mm at a slit width of 300 µm and provides a flux greater than 1 × 10(11) photons s(-1) (0.1% bandwidth)(-1). A vacuum-compatible cell made of two CaF(2) windows has a variable path length from 1.3 µm to 1 mm and a temperature range of 253-363 K. Measured CD spectra of (1S)-(+)-10-camphorsulfonic acid and proteins demonstrated the ability of this system to extend the wavelength down to 172 nm in aqueous solution and 153 nm in hexafluoro-2-propanol.