SARX 2016 Confirmed Lectures

In 1923, Arthur Compton discovered the phenomenon of total reflection of X-rays. He found that the reflectivity of a flat target strongly increased bellow a critical angle of only 0,1o. Fifty years later, in 1971, Yoneda and Horiuchi first took advantage to this effect. They proposed the analysis of a small amount of material deposited on a flat totally reflecting support. This idea was subsequently implemented in the so-called total reflection X-ray fluorescence (TXRF) analysis which has spread out worldwide. Nowadays, TXRF is a recognized analytical tool with high sensitivity and low detection limits, down to the femtogram range. It is being used in geology, biology, materials science, medicine, forensics, archeology, art history, and more. In this presentation a summary of how the TXRF reaches Latin America countries is presented.

Characterization of Active Pharmaceutical Ingredients (APIs) and excipients, either as raw materials or in the finished product, is of importance in order to assess the quality of pharmaceutical products. Over the years we have studied a variety of antihistaminics, bronchodilators, anticonvulsives, antifungals, mineral supplements, among other compounds, which are part of commercial formulations available in the market. have also been studied. Some of these compounds have produced new polymorphs, new solvates, or new derivatives, upon recrystallization, heat treatment, grinding, reactions with metal salts, sometimes under relatively mild conditions.

In this presentation, examples of the use of ICDD's PDF-4/Organics database will be presented to illustrate its capabilities in the characterization of pure APIs and excipients and of these materials in commercial formulations.

In X-ray fluorescence analysis, spectra present singular characteristics produced by the different scattering processes. When atoms are irradiated with incident energy lower but close to an absorption edge, scattering peaks appear due to an inelastic process known as Resonant Inelastic X-ray Scattering (RIXS) or X-ray Resonant Raman Scattering (RRS) [].

These RIXS/RRS peak presents a series of particular features; between them, a characteristic long-tail spreading to the region of lower energy. It has been recently observed that, hidden on this tail, there is valuable information about the local environment of the atom under study []. During the last five years, several works have been shown the first applications of RIXS (or RRS) for the discrimination, determination and characterization of chemical environments in a variety of samples and irradiation geometries and even combined with other spectroscopic techniques []. One of the most importamt features of experimental setup reported in these works is the use of an energy dispersive low- resolution spectrometer possibility for measuring RIXS spectra.

In this presentation, the basis, advantages, general highlights and latest applications of this novel and versatile tool for chemical state determinations will be presented and discussed.

X-ray spectroscopy is used widely in forensic science. Main strengths are its non-destructive nature, thus preserving crime evidences, its ability to identify chemical compounds, to determine elemental chemistry and, in some cases, elemental speciation. Moreover the versatility of the X-ray techniques permits the analysis of very diverse materials, -inorganic, organic, metals-, in powder, solid or liquid forms.

Different X-ray spectroscopy based tools, just as many other analytical techniques, have been used in forensic science for several decades. Classical X-ray based techniques used in forensic work are X-ray powder diffraction (XRD), X-ray fluorescence (XRF), X-ray imaging and Energy dispersion X-ray Emission linked to an electron microscope (SEM-EDX). These complementary techniques are mainly used in micro- and macrotrace analysis. Conventional XRF, whilst attractive for the forensic analyst, sometimes cannot be applied because in the majority of cases crime scene specimens are microscopic in nature. A common bench-top XRF system has an analysis spot of perhaps 2–4 cm, and is unsuited to perform, for instance, analysis of a 100 μm fragment.

During the last twenty years, noticeable development was made in the instrumental aspects of X-ray spectrometry, especially in the improvement of X-ray optics and detection systems. All this resulted in a wide variety of instrumentation becoming available today. Significant advances in focusing optics (development of collimators and polycapillary lenses) have promoted the design of micro beam sources or the analysis of small regions by X-ray instrumentation employing conventional X-ray tubes as the source of primary radiation. The use of automatized XYZ stages allows the possibility to do point, line profile or mapping analyses. A microscopic particle from a crime scene can be directly analysed without any sample preparation, simply located using optical cameras, and subsequently characterized for elemental content.

Along the presentation a selection of real forensic evidence types and their analysis by XRS methods (XRD, XRF, micro-EDXRF) will be described, such as glassy fragments, cosmetics, healthcare products, gunshot residues and counterfeit currency.

The emission of characteristic lines after x-ray excitation is usually explained as the consequence of two independent and consecutive physical processes: the photoelectric ionization produced by the incoming photons and the successive spontaneous atomic relaxation. However, this is not the only mechanism for the formation of the characteristic lines. In first place, the photoelectric effect is not the only ionization mechanism driven by the incoming photons. As it has been recently shown [1], Compton ionization is another possible process which contributes not negligibly to the ionization of the shells L and M. In second place, secondary electrons from these two interactions, photoelectric and Compton, are also able to ionize the atom by means of the so called impact ionization. This contribution has been recently described showing that it can be more relevant at monochromatic energies which are specific of certain lines and elements [2,3]. A third mechanism of line modification is the so called self-enhancement produced by absorption of the tail of the Lorentzian distribution of the characteristic line [4,5]. These four effects concur to the formation of the characteristic line and must be considered to obtain a precise picture in terms of the shell and the element.

This article furnishes a review of these contributions and their formal theoretical descriptions. It is given a complete picture of the photon kernel describing the emission of characteristic x- rays comprising the major photoelectric contribution and the three effects of lower extent. The line formed with all these contributions can then be followed along successive photon interactions in deterministic or Monte Carlo photon codes to describe better the multiple scattering effects.

Phytoextraction technologies use plants to extract toxic metals from contaminated soils and accumulate them in the harvestable parts of the plants, which can then be removed from site.

This work describe preliminary results of the phytoextracion capacity of two kind of vegetable species: hyperaccumulator plant species such as Brassica napus and fast-growing non-hyperaccumulator plants such as Festuca arundinacea and Lolium perenne.

Preparation of contaminated soil, seed selection, seeding, control of handling plant growth variables, selective harvesting and preparation of samples were done at CEPROCOR. The measurements were carried out at the D09B-XRF Fluorescence beamline of the LNLS and were performed in situ on different parts of the plant (roots and leaves) and in living conditions.

SR micro XRF results showed that Brassica napus extracted Pb from the ground and translocated it to the leaves more effectively than Festuca arundinácea and Lolium perenne plants grown in contaminated soil, where lead remained at the root. Furthermore, a co-distribution was observed between Pb and Zn, P, S and Fe.

SR μXRF technique offers a powerful approach for probing and mapping the distribution of Pb in selected sections of plant tissues.

Acknowledgement This work was developed at CEPROCOR and Brazilian National Synchrotron Light Laboratory under the proposals XRF-18934 and XAFS1-16907. The authors would like to thank the LNLS staff for its technical support, and also we would like to thank the CEPROCOR for supporting the project of Phytoremediation.

References
[1] Donner E and col, Mapping Element Distributions in Plant Tissues Using Synchrotron XRF Techniques. Chapter 9, 2012.
[2] Lombi E and col, In situ analysis of metal(loid)s in plants: State of the art and artefacts. Environmental and Experimental, Botany, 72, 2011, 3-17.
[3] Sarret G and col., Use of Synchrotron-Based Techniques to Elucidate Metal Uptake and Metabolism in Plants, Chapter 1, Advances in Agronomy, 2013, 1.
[4] Rubio M et al. Study of lead levels in soils by weathering of metallic Pb bullets used in dove hunting in Córdoba, Argentina. X-Ray Spectrom. March 2014.

Scientific researches for studies and analysis of art and cultural heritage objects are routinely carried out in Europe and the United States, in Brazil these studies and analyses are more recent but are growing steadily. Since 2003 the Applied Physics Group with accelerators at the Physics Institute of the University of São Paulo (IF-USP) has been working with various methodologies for characterization and analysis of the cultural heritage objects. Initially, the analysis methods were restricted to techniques using ion beam analyses such as PIXE (Particle Induction X- Ray Emission) and RBS (Rutherford Backscattering), performed at the Laboratório de Análises de Materiais por Feixes Iônicos da Universidade de São Paulo (LAMFI-USP) [1]. However, since that period, alternative methodologies and procedures of analysis has been incorporated to a better characterization of the objects, which possess distinct physical characteristics and high cultural and monetary value. The examinations in this kind of objects were expanded to others non-destructive analytical techniques with portable equipment such as EDXRF (Dispersive Energy X-ray Fluorescence), Raman and imaging analysis which coupled allow a better understanding of materials and techniques used in the creative and the manufacturing process of the objects, as well as to assist in restoration and preventive conservation work. The analyses using portable equipment has been carried out in the museums and are supported by professionals such as curators, restores and conservators. In 2012 was also created at the University of São Paulo an Applied Physics Research Group to Study of Artistic and History Patrimony (NAP-FAEPAH) [2], which brings together professionals from different fields in an interdisciplinary project to study and to characterize o different objects the museum's collections of the University. This core has a partnership with professionals of the different areas: Museum of Contemporary Art (MAC-USP), Museu Paulista (MP-USP), Museum of Archaeology and Ethnology (MAE-USP) and Brazilian Studies Institute (IEB-USP) and Institute of Physics and Polytechnic School. These new procedures of analysis aim to enable better analytical research in archaeology, artistic and cultural heritage objects and to supply results that subsidize authenticity investigations of art objects and the origin of archaeological artefacts, while stimulating the archeometry and “arteometry” research in the Brazilian Museums. The results of the different work carried out are providing new information to researchers and collaborators from different museums and institutions of the São Paulo museums group.

X-Ray Powder Diffraction, one of the premier techniques used in the characterization of materials, was invented one hundred years ago. Its origins can be traced to two landmark contributions presented to the scientific community in 1916. They are the better known and celebrated work carried out by Paul Scherrer under the guidance of Peter W. Debye [1] at the University of Göttingen, Germany, and the less known work of Albert W. Hull [2] performed at the Research Laboratory of the General Electric Company, Schenectady, NY, USA. The great contributions of Scherrer and Debye have been prominently recognized. They are presented in many textbooks and in the specialized literature in the area of structural characterization of materials using X-ray diffraction techniques. The camera designed by them, later called “the Debye-Scherrer camera”, was used extensively for many years and the experimental set up (“the Debye-Scherrer geometry”) is still used today. On the other hand, in his pioneering study, Hull presented the crystal structure of Fe obtained using powder diffraction data. Hull explained in details the methodology used in the Fe work and in the determination of the structure of other metals in a more elaborate contribution published in December of 1917. [3]

In this communication, a brief review of the contributions Peter W. Debye, Paul Scherrer and Albert W. Hull to X-Ray Powder Diffraction and to Crystallography will be presented.

This lecture presents a brief historical summary of how different X-ray techniques have been consolidated and have been developed in medical applications such as medical imaging and radiotherapy. It is presented how the EDXRF technique has been positioning in this area and has been developing as a new technique for basic medical imaging and radiotherapy. Also, it is given some projects of our research group Firax (spanish acronym of X Radiation Physics) currently carried out.

The Powder Diffraction File was first published 75 years ago. It was based on a 1938 publication in Industrial Engineering [1] entitled, "Chemical Analysis by X-ray Diffraction" which the editors described as a "complete, new, workable system of analysis". The first issue of The Powder Diffraction File (PDF™) in 1941, not only contained a database, but the data were sorted in a specific sequence, so that one could use a file index and search/match process (Hanawalt system) to identify unknowns.

Today's databases use a relational database format with JAVA interfaces so that the data can be sorted and displayed. Embedded software uses 65 searches and 119 display fields all of which can be combined to produce an almost infinite variety of data mining possibilities. The data entries themselves not only contain diffraction data but also nomenclature, structural classifications, crystallographic and physical property data. This system has been developed by global scientists, many of whom are ICDD members, for the purpose of materials analysis and continuously evolves. In recent years we have focused on expanding the range of materials analyses to include non-crystalline and amorphous materials and modulated structures. In addition, the PDF and embedded software now has the ability to analyse data from any of the world's high energy neutron or synchrotron facilities. This enables users to analyse the data at the facility or local laboratory. Intense editorial review, quality assessment and structural classification has been applied to develop the world's most complete collections of minerals, metals and alloys, ceramics and pharmaceuticals. Quality review and classification improves the accuracy of material identification and quantitative analysis. A large number of software applications have been embedded with the database to provide a wide range of materials analysis, these will be reviewed and described.

Positron emission tomography (PET) is a nuclear medical imaging technique that is commonly used to image cancer, heart disease, and brain function. The past ~15 years have seen many advances in PET instrumentation. The fraction of the body that is imaged has expanded by an order of magnitude and x-ray CT scanners are now mounted in the same gantry as the PET camera so that anatomical images from CT can be fused with the functional information from PET (i.e., the PET image shows which tissue is cancerous, while the CT image shows where this cancer is located in the patient’s body). Dual- modality systems containing a PET camera and a MRI scanner (magnetic resonance imaging, which provides anatomical images with better soft-tissue contrast than x-ray CT) are now commercially available. The efficiency for detecting the injected radiation has been increased dramatically, but this greatly increases the flux of radiation that the detectors must process, and so new scintillator materials capable of higher speed operation have been developed. PET cameras dedicated to imaging specific forms of cancer, such as breast cancer or prostate cancer, have also been developed. In the research arena, PET has been found to be extremely valuable for studying biological function in animals, especially mice. This has spurred the development of PET cameras optimized for imaging mice that boast spatial resolutions better than 1 mm fwhm. Time- of-flight PET, which reduces the statistical noise in the images, has experienced a major rebirth. Despite these impressive advances, the instrumentation still limits the performance of PET in many ways. In a typical PET study, only about 25% of the detected coincidences are “true” events—the other 75% are background event either from events that have undergone Compton scatter in the patient (roughly 25% of the events) or random coincidences (up to 50% of the events). The 511 keV gamma rays from positron annihilation can penetrate a significant distance into the scintillator crystals before they interact and are detected, which degrades the spatial resolution. The amount of radiotracer that can be injected into the patient is limited by safety concerns (radiation dose), so statistical noise (due to detecting fewer events than desired) limits the image quality. For animal PET, it is very desirable to image awake (rather than anesthetized) animals, as the anesthesia can significantly alter biological function. Finally, work needs to be done on how to evaluate how improvements in instrumentation translate into improvements in clinical practice and patient care. This presentation will describe these recent advances in more detail, list the needs that are presently unmet, and illustrate how some evolving technologies may help to meet these needs.