Previous work, by this and other authors, noted several elements in bones and teeth are distributed non-uniformly. It was theorized that elemental distributions may be accentuated in the case of bacterial infections. Regions of bone surrounding Dental Abscess and Tuberculosis lesions were identified from, Varden (AdHa-1) and LeVesconte, Ontario; San Pedro, Belize and Kellis II Cemetery, Egypt. The abscess cavities were excised intact and cross-sectioned through the identified lesion. Elemental distributions in the bones were obtained using Synchrotron X-ray Fluorescence mapping. Maps of Zinc, Copper, Iron and Bromine were collected from the samples. The elements included in this study displayed no correlation between distribution patterns and the presence of a dental abscess. This conclusion is limited to the elements studied. Other elements or possible effects on bone structure, crystallinity or elemental chemistry will need to be addressed in future work. However, it was found that Zinc concentration correlates with active bone formation areas.

Cobalt silicide thin films, prepared on Si(100) wafers, have been studied by X-ray absorption near edge structures (XANES) at the Si K-, L 2,3 and Co K-edges utilizing both total electron (TEY) and fluorescence yield (FLY) detection as well as extended X-ray absorption fine structure (EXAFS) at the Co K-edge. Samples made using DC sputter deposition on clean Si surfaces and MBE were studied along with a bulk CoSi 2 sample. XANES and EXAFS provide information about the electronic structure and morphology of the films. It was found that the films studied have essentially the same structure as bulk CoSi 2 . Both the spectroscopy and materials characterization aspects of XAFS (X-ray absorption fine structures) are discussed.

Platinum silicide films, with a typical thickness of several hundred Å, prepared on n-type Si(100) wafers by UHV mnagnetron sputter deposition followed by rapid thermal annealing, have been studied by Si L2,3-edge X-ray absorption near edge structure (XANES) using both total electron and total fluorescence yield detection. Samples of various annealing times were studied. XANES provides information on the electronic structure and morphology of the samples. By utilizing the sampling depth difference between the two detection methods, we can clearly see XANES data from each layer (eg. surface oxide, silicide) in the sample and can estimate the thickness of the oxide layer.

Periodontitis is a serious disease that affects up to 50% of an adult population. It is a chronic condition involving inflammation of the periodontal ligament and associated tissues leading to eventual tooth loss. Some evidence suggests that trace metals, especially zinc and copper, may be involved in the onset and severity of periodontitis. Thus we have used synchrotron X-ray fluorescence imaging on cross sections of diseased and healthy teeth using a microbeam to explore the distribution of trace metals in cementum and adhering plaque. The comparison between diseased and healthy teeth indicates that there are elevated levels of zinc, copper and nickel in diseased teeth as opposed to healthy teeth. This preliminary correlation between elevated levels of trace metals in the cementum and plaque of diseased teeth suggests that metals may play a role in the progress of periodontitis.

This chapter provides an overview of the current state-of-the-art for assessing speciation and attenuation of contaminants in the terrestrial environment. Given that speciation and attenuation influence chemical bioavailability, the chapter discusses application of isotopic dilution techniques to bioavailability assessment. A series of case studies is provided that exemplify cutting-edge techniques and methodologies for assessing the role of chemical speciation and natural attenuation on the bioavailability of contaminants in the terrestrial environment. A summary is presented of the findings of the techniques and case studies presented to reinforce the strength of the techniques described. The strength of synchrotron-based spectroscopic techniques is explained. Through the application of XANES, it is demonstrated that Cr is present in ambient particulate matter in a wide variety of forms that probably represent an equally broad set of sources. Basics of the isotopic dilution principle are elaborated. Also,details of microbeam synchrotron X-ray fluorescence of human teeth are provided. An overview of XANES and EXAFS analyses of arsenic in soils is also presented.

Synchrotron radiation analysis has been used to study the trace metal distribution in the cementum rings of selected human teeth. The resulting patterns can be used to identify regions within the root cementum, where the metals are unambiguously endogenous. Since the cementum is thought to display annual growth rings the ability to distinguish endogenous from diagenetic deposition in the trace metal content of the cementum rings, may provide a chronology of an individual's metal exposure.

Synchrotron radiation analysis was used to investigate the metal content of tree rings collected from paper birch, Betula papyrifera Marsh, on transects downwind from two metal smelters (nickel and copper). Individual trees reflected changes in ring metal content with time, which may be presumed to represent changes in local metal bioavailability. However, between-tree variations were large and no statistically significant differences in metal content as a function of time were found within or between sites. Although concentrations of both total and exchangeable copper and nickel in the soil increased with proximity to the respective smelter, this pattern was reflected only in the nickel content of rings near the nickel smelter; copper content did not vary with distance from either smelter. The sites did differ with respect to lead, manganese and zinc content of the rings, which may be related to pH. In conclusion, the variability between trees at each site suggests that dendroanalysis is a poor method for evaluating metal exposure at a large (site) scale. Tree ring metal content may be used to evaluate the metal uptake by individual trees but metal mobility in the stem makes it difficult to establish a reliable chronology. Copyright (c) 2005 John Wiley & Sons, Ltd.

Photoluminescence from Alq3 (tris-aluminum-8-hydroxyquinolinate) excited with synchrotron light in both the UV (5 –20eV) and the soft X-ray (Al K-edge) region are reported and are compared with results with excitation at the K-edge energies of C, N and O. X-ray emission excited with photon energy above the carbon and the nitrogen K-edge are also reported. It is found that the luminescence is sensitive to the excitation channel and can be interpreted in terms of the C and N K-edge X-ray absorption near edge structures (XANES) and X-ray emission spectroscopy (XES) results as well as a recent theoretical calculation.

Synchrotron X-ray fluorescence has been used to study the distribution of lead in a hair sample collected from a lead smelter worker. A mathematical model was used to imitate the transverse scan signal based on the analysis volume and concentration profiles. The results suggest that the Pb originates both from ingestion and environmental exposure, however direct deposition from the environment is the more important source of hair lead. The model could apply equally to any other analysis involving a thin cylindrical sample.

Time of flight secondary ion mass spectroscopy has been used to study the metal distribution at the soil/root interface of tree roots extracted from smelter-impacted soils. The results, augmented by scanning electron microscopy, show that the technique is capable of resolving metal distributions at the cellular level. In addition, the distribution of metals between the root plaque and the root interior may be useful in interpreting local metal transport mechanisms.

We report a soft x-ray excited optical luminescence (XEOL) and x-ray emission spectroscopy (XES) study of silicon nanowires (SiNW) with excitations at the silicon K and L-3,L-2 edge, respectively. It is found that the XEOL of SiNW exhibits several luminescence bands at similar to460, similar to530, and similar to630 nm. These luminescence bands are broad and are sensitive to the Si 1s excitation channel (Si versus SiO2 whiteline). These chemical- and morphology-dependent luminescences are attributable to the emission from the encapsulating silicon oxide, the quantum-confined silicon crystallites of various sizes embedded in the oxide layer, and the silicon-silicon oxide interface. XES clearly shows the presence of a relatively thick oxide layer encapsulating the silicon nanowire and the densities of states tailing across the Fermi level. The implications of these findings to the electronic and optical properties of silicon nanowires are discussed.

Synchrotron micro X-ray fluorescence has been used to study differences in the trace element concentration between the dentine and cementum rings of human teeth. The results show that metals such as zinc are concentrated in the cementum rings. This suggests that if the rings are deposited annually a temporal record of metal exposure may be extracted from this material.

Samples of sewage sludges proposed for use as soil ameliorants in an Indo-Canadian project were tested for chromium content. Standard aqua regia extractions found one sludge to have excessive amounts of Cr. X-ray absorption near-edge structure (XANES) spectroscopy, however, indicated that the Cr was present in the relatively benign Cr(III) oxidation state in all the sludge samples.Key words: soil, chromium, synchrotron, XANES.

Micro-synchrotron radiation x-ray fluorescence has been used to examine the metal distribution across an entire black spruce stem. The results show the individual elements to be transported and sequestered in different ways so that apparent elemental mobility within the stem changes from element to element. The results suggest that a detailed knowledge of the behavior of each element is required before pollution chronologies can be inferred from dendroanalysis. Copyright (C) 2003 John Wiley Sons, Ltd.

X-ray excited optical luminescence (XEOL) using tunable soft x rays from a synchrotron light source, together with x-ray absorption fine structure spectroscopy has been used to study the electronic structure and optical properties of thin films of poly(N-vinylcarbazole). It is found that carbon core level excitation enhances the formation of excimers emitting at 380 and 410 nm. A third excimer at 310 nm is also noted. In addition, excitations across the C K edge and the N K edge show noticeably different optical response. These results are interpreted in terms of the site specificity of the XEOL technique.

X-ray excited optical luminescence (XEOL) studies of several classes of light emitting materials excited using soft x rays (photon energy ranging from 10 to 2500 eV) are presented. We show that XEOL with soft x rays (short penetration depths) is often site specific and is ideally suited for the study of light emitting thin films and devices. Several examples including porous silicon, organic light emitting diode materials, and CdS based nanostructures are used to illustrate the unique properties of XEOL and its applications in the soft x-ray energy region.

Electrochemically deposited CdS nanoparticles (NPs) were formed using porous silicon (PS) as a substrate/electrode. The structure, electronic behavior of the CdS NPs and the interaction between CdS-PS were systematically examined using electron microscope, X-ray diffraction and X-ray absorption fine structure (XAFS) at S K-edge and Si K-edge. The optical luminescence behavior of the nanocomposite, CdS/PS, was also investigated with the technique of synchrotron X-ray excited optical luminescence (XEOL), which was proved to be a unique tool to distinguish the luminescence originated from both CdS and PS.