RESUMO
Details of the design and operational status of the silicon-nitride-based entrance slit installed in the Taiwan Photon Source (TPS) 45A beamline are given. The slit is a diamond blade edge etched onto a copper slit part, which is in thermal contact with the silicon nitride base. A stable slit opening smaller than 4â µm is achieved in TPS 45A. The beam size at the slit has a full width at half-maximum of 3â µm in the vertical direction with a power of 20â W. Additionally, a hard stop made of invar is incorporated to control the thermal expansion displacement. The slit reduces the size and increases the stability of the source of the monochromator. Consequently, a higher energy resolution and excellent beamline stability are achieved.
RESUMO
A digital autocollimator of resolution 0.1â µrad (0.02â arcsec) serves as a handy correction tool for calibrating the angular uncertainty during angular and lateral movements of gratings inside a monochromator chamber under ultra-high vacuum. The photon energy dispersed from the extreme ultraviolet (XUV) to the soft X-ray region of the synchrotron beamline at the Taiwan Light Source was monitored using molecular ionization spectra at high resolution as energy references that correlate with the fine angular steps during grating rotation. The angular resolution of the scanning mechanism was <0.3â µrad, which results in an energy shift of 80â meV at 867â eV. The angular uncertainties caused by the lateral movement during a grating exchange were decreased from 2.2â µrad to 0.1â µrad after correction. The proposed method provides a simple solution for on-site beamline diagnostics of highly precise multi-axis optical manipulating instruments at synchrotron facilities and in-house laboratories.
RESUMO
During the last 20 years, beamline BL08B has been upgraded step by step from a photon beam-position monitor (BPM) to a testing beamline and a single-grating beamline that enables experiments to record X-ray photo-emission spectra (XPS) and X-ray absorption spectra (XAS) for research in solar physics, organic semiconductor materials and spinel oxides, with soft X-ray photon energies in the range 300-1000â eV. Demands for photon energy to extend to the extreme ultraviolet region for applications in nano-fabrication and topological thin films are increasing. The basic spherical-grating monochromator beamline was again upgraded by adding a second grating that delivers photons of energy from 80 to 420â eV. Four end-stations were designed for experiments with XPS, XAS, interstellar photoprocess systems (IPS) and extreme-ultraviolet lithography (EUVL) in the scheduled beam time. The data from these experiments show a large count rate in core levels probed and excellent statistics on background normalization in the L-edge adsorption spectrum.
RESUMO
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 130-330â nm. The light spot at the sample position is 5â mm × 5â mm at a slit width of 300â µm and provides a flux greater than 1 × 10(11)â photons s(-1) (0.1% bandwidth)(-1). A vacuum-compatible cell made of two CaF(2) windows has a variable path length from 1.3â µm to 1â mm and a temperature range of 253-363â K. Measured CD spectra of (1S)-(+)-10-camphorsulfonic acid and proteins demonstrated the ability of this system to extend the wavelength down to 172â nm in aqueous solution and 153â nm in hexafluoro-2-propanol.
Assuntos
Cânfora/análogos & derivados , Dicroísmo Circular/métodos , Proteínas/química , Síncrotrons/instrumentação , Cânfora/química , Concanavalina A/química , Mioglobina/química , Dobramento de Proteína , Estrutura Secundária de Proteína , Soroalbumina Bovina/química , SoluçõesRESUMO
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.