CONTACT & STAFF
Facility E-mail: jatoba@lnls.br
Project Coordination: Helio Tolentino and Rodrigo Szostak
The JATOBÁ beamline is being built to produce a high-energy, high-photon flux beam focused on micrometric dimensions. It will be dedicated to the study of a wide range of materials using the full X-ray scattering technique. The beamline should start operation for preliminary test experiments during the first semester of 2026.
The total scattering technique encompasses both Bragg diffraction from crystalline structures and diffuse scattering, which is related to short-range order effects and without the need for crystalline ordering. The signal obtained from the total scattering experiment is used to obtain the function known as PDF (Pair Distribution Function). The PDF function is an oscillatory function, and each peak represents in r (interatomic distance) the probability of finding a pair of atoms and is weighed by the scattering power of the pair of atoms [1]. Thus, based on total scattering experiments on the Jatobá beamline and the calculation of the PDF function, it will be possible to obtain information on the local order of amorphous and nanostructured materials, such as interatomic distances, degrees of disorder and coordination. [1].
JATOBÁ is essentially an X-ray scattering beamline, like the PAINEIRA beamline, for diffraction of polycrystals. However, to promote full X-ray scattering and PDF analysis experiments, it will deliver high energy X-rays, between 41 and 68 keV, corresponding to short wavelengths (0.3 to 0.18 Å), high Q (scattering vector modulus) between 20 and 30 Å-1 and high photon flux (1013ph/s /100mA at 41keV) at the sample position. In addition, the beamline will be equipped with cell reaction, sample horder, gas-handlings systems, and heating and cooling systems. This infrastrutre will allow kinetics experiments in situ and operando conditions to study functional materials, such as catalysts, energy storage, and energy conversion devices, for example.
[1] Egami, T. & Billinge, S. J. L. (2012). Underneath the Bragg Peaks: Structural Analysis of Complex Materials, 2nd ed. Amsterdam, Elsevier.
Facility E-mail: jatoba@lnls.br
Project Coordination: Helio Tolentino and Rodrigo Szostak
X-ray diffraction (XRD), or WAXS, is one of the most established and used techniques among the several techniques that use synchrotron light. When reaching a crystal, X-ray photons are scattered by the electrons that make up the crystal and that are distributed periodically in the crystalline structure. This periodicity, of the same order as the X-ray wavelength, works as a diffraction grid that scatters the light in an inhomogeneous way. In some directions, the scattered light contributes constructively, generating what is called Bragg peak. The arrangement of these peaks, together with the incident beam energy, allows to determine the relative position of the atoms that make up the crystal. In the case of materials composed of a large number of theses crystals – usually of micro or nanometric dimensions composing a polycrystal – an average over all the polycrystalline material is made, and the diffractogram appears in the form of scattering rings around the direction of the incident beam. A finer modeling of these peaks allows to determine not only the crystalline phase but also deformations in the crystalline network due to stress conditions and/or atomic inclusions.
Beyond collecting conventional diffraction patterns, as in the case of the PAINEIRA beamline, a unique capacity of JATOBÁ beamline is the possibility to probe a wider region of the reciprocal space (20-30 A-1), due to the high photon energy associated with large area detectors. In this technique, total scattering pattern (diffractograms going to high Q) is normalized by the scattering factor and transformed to the function known as the Pair-Distribution Function (PDF) by Fourier Transform. It results in an oscillatory function in real space where the peaks represent the probability of finding a pair of atmos. The PDF gives information about the short and medium-range order, complementary to the long-range order of diffraction in polycrystals [1]. Even materials that are completely amorphous can be analyzed using PDF, which is not possible with the diffraction technique.
With an incident beam of micrometric dimensions and translation stages, as is the case with JATOBÁ, it is possible to map regions with different crystallinities in the sample. Various types of analysis of nanostructured and/or poorly ordered materials will be possible through 2D mapping with micrometric spatial resolution and short, medium, and long-range order contrast through the PDF and WAXS techniques. These images are obtained by means of high–precision scanning to position the sample in relation to the micrometric beam of synchrotron light.
The sample stage will also be equipped with a rotation stage, which will allow the measurement of computed tomography (CT). The experiment relies on crossing the sample laterally with line scans combined by rotation. At each position and rotation, the detector records one 2D scattering pattern. After data reduction, a 3D sinogram is built, and then a reconstruction algorithm returns the final image. In this image, each pixel/voxel corresponds to a scattering pattern. If recorded with sufficient maximum Q, the scattering pattern of each pixel/voxel can be processed to obtain a PDF and consequently obtain a PDF-CT. In the same way, XRD-CT can be obtained. An image can be obtained by choosing a PDF peak (pair distance) or a Bragg peak. This technique allows us to characterize the interior of the materials.
Thin films deposited in thick substrates are common in several scientific areas. The PDF can be obtained in transmission geometry, but the low film-to-substrate ratio makes it difficult to analyze. An alternative to better characterize this sample is to use grazing incidence geometry, which provides an increased surface sensitivity of the scattering intensity. The JATOBÁ beamline will also be equipped with a goniometer, allowing us to measure samples in GI conditions. GIWAXS and the emerging GIPDF techniques will be available.
| Element | Type | Position [m] | Description |
|---|---|---|---|
| SOURCE | Dipole (BC) | 0 | BC |
| ML1 | Multilayer Toroidal Mirror | 15 | Radiation extraction and focusing |
| ML2 | Multilayer Plane Mirror | 28 | Fine selection of energy |
| SE | Sample holder | 30 | Sample handler and environment |
| DET | Detector | 32 | 2D Detector |
The JATOBÁ beamline is designed to use the BC source by selecting three energies (E1, E2, E3) using multilayer mirrors.
| Parameter | E1 | E2 | E3 |
|---|---|---|---|
| Energy range [keV] | 41.2 | 54.7 | 68.3 |
| Wavelength [Å] | 0.30 | 0.23 | 0.18 |
| Qmax [Å-1] | 20-30 | 20-30 | 20-30 |
| Energy resolution (ΔE/E) [%] | 0.86 | 0.42 | 0.20 |
| Photon flux [photons/s/100mA] | 1.48 x 1013 | 4.00 x 1012 | 9.47 x 1011 |
| Beam size [μm2, H x V – FWHM] | ~ 22 x 20 | ~ 22 x 20 | ~ 22 x 20 |
* Depends on the detector size and distance