Lead uptake in diverse plant families: A study applying X-ray absorption near edge spectroscopy

The chemical environment of lead in roots and leaves of plants from four different plant families and a lichen from a former lead mining site in the Eifel Mountains in Germany was determined by Pb L3-edge XANES measurements using solid reference compounds and also aqueous solutions of different ionic strength simulating the plant environment. Pb2+ ions in the plants were found to have two major coordinations, one with nine oxygen atoms in the first coordination shell similar to outer-sphere complexation and a second coordination with just three oxygen atoms similar to inner-sphere complexation. This can be interpreted assuming that lead is sorbed on the surface of cell walls depending on the concentration of lead in the soil solution. Pb L3-edge XANES spectra of dried and fresh plant samples are very similar because sorption does not change with removal of water but only because of the initial ionic strength. No bonding to biologically important groups (-S, - N) or precipitation (-PO4) was found. © 2013 American Chemical Society

SOLARIS National Synchrotron Radiation Centre in Krakow, Poland

The SOLARIS synchrotron located in Krakow, Poland, is a third-generation light source operating at medium electron energy. The first synchrotron light was observed in 2015, and the consequent development of infrastructure lead to the first users’ experiments at soft X-ray energies in 2018. Presently, SOLARIS expands its operation towards hard X-rays with continuous developments of the beamlines and concurrent infrastructure. In the following, we will summarize the SOLARIS synchrotron design, and describe the beamlines and research infrastructure together with the main performance parameters, upgrade, and development plans

ELECTRONIC-STRUCTURE OF THIOMETALATES [MS4](N-) (M=MO, W, RE) - XANES SPECTRA AND SCF-X-ALPHA-SW CALCULATIONS

Müller A, Wittneben V, Diemann E, Hormes J, Kuetgens U. ELECTRONIC-STRUCTURE OF THIOMETALATES [MS4](N-) (M=MO, W, RE) - XANES SPECTRA AND SCF-X-ALPHA-SW CALCULATIONS. CHEMICAL PHYSICS LETTERS. 1994;225(4-6):359-363.Sulfur K-edge XANES spectra of PPh4+ salts of the title species are reported. Assignments for the characteristic positions in the spectra are given and discussed. The energies of the pre-edge peaks and the main absorption edges are used to determine the ''crystal-field' splitting energies DELTA, i.e. the energy difference between the 2e and 4t2 levels (1.4 eV for [ReS4]-, 1.1 eV for [WS4]2-and [MoS4]2-) and the energies of some frontier orbitals (HOMO-LUMO region). These data are compared with results from Xalpha calculations, electronic absorption and ESCA spectra

SULFUR-EDGE X-RAY ABSORPTION NEAR EDGE SPECTRA (XANES) OF SOME THIOMETALLATES AND THIOMETALLATO COMPLEXES

Wittneben V, SPRAFKE A, Diemann E, et al. SULFUR-EDGE X-RAY ABSORPTION NEAR EDGE SPECTRA (XANES) OF SOME THIOMETALLATES AND THIOMETALLATO COMPLEXES. JOURNAL OF MOLECULAR STRUCTURE. 1989;198:525-529

Functionalization of gold and glass surfaces with magnetic nanoparticles using biomolecular interactions

Advances in nanotechnology have enabled the production and characterization of magnetic particles with nanometer-sized features that can be functionalized with biological recognition elements for numerous applications in biotechnology. In the present study, the synthesis of and interactions between self-assembled monolayers (SAMs) on gold and glass surfaces and functionalized magnetic nanoparticles have been characterized. Immobilization of 10-15 nm streptavidin-functionalized nanoparticles to biotinylated gold and glass surfaces was achieved by the strong interactions between biotin and streptavidin. Fluorescent streptavidin-functionalized nanoparticles, biotinylated surfaces, and combinations of the two were characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and electron and fluorescent microscopy to confirm that little or no functionalization occurred in nonbiotinylated regions of the gold and glass surfaces compared to the biotinylated sites. Together these techniques have potential use in studying the modification and behavior of functionalized nanoparticles on surfaces in biosensing and other applications

Site-Selective High-Resolution X‑ray Absorption Spectroscopy and High-Resolution X‑ray Emission Spectroscopy of Cobalt Nanoparticles

The special (macroscopic) properties of nanoparticles are mainly due to their large surface-to-volume ratio. Thus, the separate characterization of geometric and electronic properties of surface and bulk would be favorable for a better understanding of the properties of nanoparticles. Because of the chemical sensitivity of X-ray fluorescence lines, in particular those involving higher lying electronic states, high-resolution fluorescence-detected X-ray absorption spectra (HRFD-XAS) offer these opportunities. In this study, three types of wet-chemically synthesized Co nanoparticles, ∼6 nm in diameter with varying thicknesses of a protective shell, were investigated at the ID26 beamline of the European Synchrotron Radiation Facility. HRFD-XAS spectra at the Co K-edge, that is, X-ray absorption near-edge structure (HRFD-XANES) and extended X-ray absorption fine structure (HRFD-EXAFS) spectra, were recorded via detection of the Kβ_1,3 fluorescence at specific energies. As these spectra are only partly site-selective due to a strong overlap of the emission lines, a numerical procedure was applied based on a least-squares fitting procedure, realized by singular value decomposition. The detailed analysis of the obtained site-selective spectra, regarding chemical composition and crystallographic phase, using measured and simulated FEFF9-based reference spectra, showed that the metallic core had mainly hexagonal close-packed structure with lattice constants matching bulk Co; the spectra for the shell could be satisfactorily fitted by a mixture of CoO and CoCO₃; however, with an obvious need for at least a third compound. To obtain additional information about ligands attached to Co, valence-to-core X-ray emission spectra (VTC-XES) using the Kβ_2,5 and the satellite structure Kβ″ and VTC-XANES spectra thereof were also recorded, by which the former results are confirmed. Further on, FEFF simulations indicate that a Co–N compound is a very likely candidate for the third component. The presented results clearly show that VTC-XES and HRFD-XAS are suitable tools for the detailed specification of the core and the surface of nanoparticles, in particular upon realizing “real” site-selectivity for XANES and EXAFS with a general strategy applicable to a wide range of systems