Helio C. N. Tolentino

Synchrotron radiation X-Ray fluorescence at the LNLS: beamline instrumentation and experiments

The x-ray fluorescence heamline of the Laboratorio Nacional de Luz Sincrotron (LNLS) is described. The main optical component of the beamline is a silicon (111) channel-cut monochromator, which can tune energies between 3 and 14 keV. A general description of two experimental stations is given. Beam characterization was done by measuring experimental parameters such as vertical profile and monochromatic flux. These results show that the photon flux at 8 keV in an area of 20 mm 2 is 4.2 × 10 9 photons s -1 . The possibility of achieving fine tuning of energies (high resolution) was confirmed. This paper presents some original results derived from the commissioning of the beamline, such as a comparison of detection limits in different experimental conditions, and a novel mechanical system to align capillaries together with a semi-automatic adjustment procedure. So far, there have been several proposals to perform a variety of experiments at this beamline, covering different fields, such as physics, chemistry, geology and biology.

The Small-Angle X-ray Scattering Beamline of the Brazilian Synchrotron Light Laboratory

This paper describes the small-angle scattering beamline built at the Brazilian Synchrotron Light Laboratory (LNLS). Vertical focusing of the synchrotron beam is achieved by an elastically bent gold-plated cylindrical mirror. An asymmetric cut curved triangle-shaped silicon single crystal (111 reflection) is used for monochromatization and horizontal focusing. The mirror, monochromator optics and 2θ arm were designed to cover the spectral range between 1.0 and 2.0 A. Three slit sets, a secondary photon shutter, two beam monitors, filters and absorbers, a multi-sample holder, a vacuum path, a beam-stopper and a set of detectors are the basic components of the workstation. The stepping motors are equipped with specially designed encoders. All mechanical and pneumatic movements and detectors can be remotely controlled using a direct panel or a PC.

Commissioning and first results of the LNLS XAFS beamline

An X-ray absorption fine-structure spectroscopy beamline has been installed and commissioned at a bending-magnet source at LNLS. Three monochromators are available: a channel-cut, a double-crystal and a four-crystal set-up. They have been operated from 2500 up to 15000 eV, with a resolving power better than 5500 in the full range. Photon flux of the order of 10(8) photons s(-1) up to 10(10) photons s(-1) has been attained. The experimental station is equipped with a table that can withstand a weight of 300 kg and track the vertical position of the beam with a 2.5 micro m accuracy over a 120 mm stroke. The beamline has been fully characterized and the first results are presented.

The soft X-ray spectroscopy beamline at the LNLS: technical description and commissioning results

The soft X-ray spectroscopy beamline installed at a bending-magnet source in the LNLS is presented. A technical description of the main elements is given and some selected commissioning results are shown. The beamline optics was designed to cover the soft X-ray energy range from 790 up to 4000 eV. The bending-magnet source has a critical energy of 2.08 keV and delivers ∼1012 photons s−1 mradH−1 (0.1% bandwidth)−1 (100 mA)−1. The focusing element is a gold-coated toroidal mirror operating at an angle of incidence of 1°. The double-crystal monochromator has three pairs of crystals which can be selected by a lateral translation. The UHV experimental station is equipped with an ion gun, an electron gun, a LEED optics and an electron analyser. The beamline is intended for X-ray absorption, photoemission, reflectivity and dichroism experiments. The beamline has been installed, commissioned, and is now open to the external users community.

Short-range charge order in R Ni O 3 perovskites ( R = Pr , Nd, Eu, Y) probed by x-ray-absorption spectroscopy

The short-range organization around Ni atoms in orthorhombic

A two-crystal monochromator for the UVX ring of LNLS

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The LNLS soft X-ray spectroscopy beamline

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High‐resolution monochromator for soft and hard x rays

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Robust perpendicular exchange coupling in an ultrathin CoO/PtFe double layer: Strain and spin orientation

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Emergence of ferromagnetism and Jahn-Teller distortion in LaMn1−xCrxO3 (x < 0.15)

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