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

Abstract

The x-ray fluorescence beamline of the Laboratorio Nacional de Luz Síncrotron (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.

Synchrotron radiation induced TXRF

“…The SR-TXRF setup at NSLS, Campinas, Brazil is also operated in a vacuum chamber; white beam excitation of a bending magnet beamline as well as monochromatic radiation from Si 111 is used. 37 The sample reflector is located vertically. Detection limits of 0.04 mg ml À1 are reported.…”

Trace element concentration in São Francisco River water using STXRF and PIXE techniques

“…The STXRF measurements were carried out using the polychromatic X-ray beam, with maximum energy of 20 keV, of the XRF line, at the National Laboratory of Synchrotron Light (LNLS), located in Campinas-SP [4]. A Si(Li) detector, with 160 eV FWHM Mn-K α line, surrounded by tantalum collimators and placed at 90 o to the incident beam, was used for X-Ray detection.…”

“…These techniques have the advantage of speed, sensitivity, simplicity, and the ability to analyze mixtures without prior treatment or separation. In this work, water samples from the São Francisco River were analyzed for trace elements at the X-ray fluorescence beam line installed at the 2.5-GeV Brazilian Synchrotron Light Source [4][5][6][7].…”

Effect of synchrotron polarization on grazing incidence X-ray fluorescence analysis

“…TXRF is another variant of the energy dispersive-XRF (EDXRF) technique, where the complexity of large spectral background eliminates to a great extent owing to the high reflectivity on the flat surface and low penetration depth of the primary x-ray beam in the substrate material, on which the incident x-rays are allowed to impinge at glancing incidence angles. All these features improves the detection sensitivities of TXRF ~ 2-3 orders of magnitude or better than the conventional XRF, typically in the range of parts per billion (ppb) levels for most of the elements 3,4 . Another approach to reduce the spectral background in x-ray fluorescence measurements is to utilize linearly polarized primary radiation for excitation 1 .…”