A dedicated small-angle X-ray scattering beamline with a superconducting wiggler source at the NSRRC

Abstract

At the National Synchrotron Radiation Research Center (NSRRC), which operates a 1.5 GeV storage ring, a dedicated small-angle X-ray scattering (SAXS) beamline has been installed with an in-achromat superconducting wiggler insertion device of peak magnetic field 3.1 T. The vertical beam divergence from the X-ray source is reduced significantly by a collimating mirror. Subsequently the beam is selectively monochromated by a double Si(111) crystal monochromator with high energy resolution (DeltaE/E approximately 2 x 10(-4)) in the energy range 5-23 keV, or by a double Mo/B4C multilayer monochromator for 10-30 times higher flux ( approximately 10(11) photons s(-1)) in the 6-15 keV range. These two monochromators are incorporated into one rotating cradle for fast exchange. The monochromated beam is focused by a toroidal mirror with 1:1 focusing for a small beam divergence and a beam size of approximately 0.9 mm x 0.3 mm (horizontal x vertical) at the focus point located 26.5 m from the radiation source. A plane mirror installed after the toroidal mirror is selectively used to deflect the beam downwards for grazing-incidence SAXS (GISAXS) from liquid surfaces. Two online beam-position monitors separated by 8 m provide an efficient feedback control for an overall beam-position stability in the 10 microm range. The beam features measured, including the flux density, energy resolution, size and divergence, are consistent with those calculated using the ray-tracing program SHADOW. With the deflectable beam of relatively high energy resolution and high flux, the new beamline meets the requirements for a wide range of SAXS applications, including anomalous SAXS for multiphase nanoparticles (e.g. semiconductor core-shell quantum dots) and GISAXS from liquid surfaces.

A small/wide-angle X-ray scattering instrument for structural characterization of air–liquid interfaces, thin films and bulk specimens

“…The dedicated SAXS beamline 23A uses the X-ray source from the in-achromat superconducting wiggler insertion device of a constant magnetic field of 3.1 T. As details of the beamline have been described in a previous report (Liu et al, 2009), here we only briefly outline the beamline optics and main features. The X-ray beam from the source is first collimated by a cylindrical mirror to decrease the vertical beam divergence by a factor of 10.…”

“…The collimation stage consists of a 10 ms beam shutter, two pinhole-slit systems, two beam-intensity monitors, two sets of attenuators, a laser alignment system and a rotary disc. The beam size is mainly defined by the first pinhole-slit system (P1) in the experimental hutch and the high-precision slits (S3) (in the beamline hutch) located 5 m before P1 (Liu et al, 2009). The guard pinhole-slit system (P2) for eliminating parasitic scattering is connected to P1 via a bellows to allow an adjustable spacing of between 0.6 and 0.9 m, and can be translated to fit a variety of sample geometries for decreasing beam path in air.…”

Synchrotron Radiation Facilities in Taiwan

“…The beamline adapts two monochromators incorporated into one rotating cradle for fast exchange: the double Si(111) crystal monochromator for high-energy resolution in the energy range of 5-23 keV, and the double Mo/B 4 C multilayer monochromator for 10-30 times higher photon flux of ~2 × 10 11 photons/s in the 6-15 keV range. A Si-based plane mirror is especially installed to selectively deflect the beam downwards with an appropriate incident angle for grazing-incidence SAXS (GISAXS) with air-liquid/liquid-liquid interfaces [12]. The high q resolution makes the study of structural evolution with a large ordering spacing of ~250 nm in a supramolecular complex feasible [13].…”

Structural characterizations of chloroplast translocon protein Tic110

“…The SAXS experiments were performed at the Beamline 23A at National Synchrotron Radiation Research Center (NSRRC) in Taiwan (Liu et al, 2009) using a MARCCD165 detector. The protein sample concentration was 1 mg ml À1 .…”