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K edge absorption of atomic iodine
Alojz Kodre, Jana Padežnik Gomilšek, Iztok Arčon, S. de Panfilis, 2008, published scientific conference contribution abstract

Found in: osebi
Keywords: rentgenska absorpcijska spektroskopija, cezij, absorpcijski robovi L, večelektronske fotoeksitacije
Published: 15.10.2013; Views: 4090; Downloads: 12
URL Fulltext (0,00 KB)

X-ray absorption spectroscopy and related techniques
Iztok Arčon, Alojz Kodre, Jana Padežnik Gomilšek, 2004, original scientific article

Abstract: In the extensive field of X-ray diagnostic techniques, nowadays mostly implemented on synchrotron X-ray sources, the X-ray absorption methods offer a relatively simple tool for structural analysis of materials. The advantage of the methods is the sensitivity to chemical species and the insensitivity to the long-range order. An overview of various detection techniques is given together with the discussion of accuracy of the method with regard to the spatial resolution and the possible contamination by intra-atomic contributions, the multielectron photoexcitations.
Found in: osebi
Keywords: X-žarki, absorpcija, EXAFS, XANES
Published: 10.07.2015; Views: 2602; Downloads: 17
URL Fulltext (0,00 KB)

High-resolution X-ray absorption spectrometry of atomic vapors
Iztok Arčon, Jana Padežnik Gomilšek, Alojz Kodre, Andrej Mihelič, 2004, original scientific article

Abstract: A measurement of an x-ray absorption spectrum of a monatomic sample yields pure atomic absorption essential for the EXAFS (Extended X-ray Absorption FineStructure) analysis in cases of a weak structural signal. A construction of an absorption cell to contain vapor sample takes into account specific properties of the investigated element. Metal-vapor absorption cells for the elements K, zn, Rb, Cd, Cs, and Hg are presented and comments are made on the use of materials and the operating mechanisms of the cells.
Found in: osebi
Keywords: X-žarki, absorpcija, EXAFS, absorpcijske celice
Published: 10.07.2015; Views: 2778; Downloads: 13
URL Fulltext (0,00 KB)

Atomic effects in EXAFS structural analysis of redox I[sup]-/I[sup]-[sub]3 solid state electrolites
Iztok Arčon, Jana Padežnik Gomilšek, Alojz Kodre, 2006, original scientific article

Abstract: Atomic effects in EXAFS structural analysis of redox Isup-/Isup-sub3 solid state electrolites
Found in: osebi
Published: 17.05.2016; Views: 2150; Downloads: 11
URL Fulltext (0,00 KB)

Specific EXAFS tools in analysis of MoSI nanowires
Anton Meden, Alojz Kodre, Iztok Arčon, Jana Padežnik Gomilšek, Dragan Mihailović, 2006, original scientific article

Abstract: Specific EXAFS tools in analysis of MoSI nanowires
Found in: osebi
Keywords: EXAFS, MoSI, nanocevke, struktura
Published: 17.05.2016; Views: 2214; Downloads: 12
URL Fulltext (0,00 KB)

Arbuscular mycorrhizal fungi alter Hg root uptake and ligand environment as studied by X-ray absorption fine structure
Alojz Kodre, Iztok Arčon, Marta Debeljak, Mateja Potisek, Matevž Likar, Katarina Vogel-Mikuš, 2017, original scientific article

Abstract: Mercury (Hg) – plant – fungal interactions are only poorly studied. Hg speciation and ligand environment in maize roots inoculated with arbuscular mycorrhizal (AM) fungi were investigated in order to better understand the role of AM in Hg soil to root transfer. The maize plants were grown in Hg polluted substrate (50 mg g1 as dissolved HgCl2) and inoculated with AM fungi originating from: a) highly Hg polluted environment of a former Hg smelting site in Idrija, Slovenia, (Glomus sp. – sample AmI), and b) non-polluted environment (commercial AM inoculum Symbivit1 – sample AmC). Hg speciation and ligand environment in maize roots was studied by Hg-L3 XANES and EXAFS with emphasis on XAS methodology – modelling and fitting the XAFS spectra to extract in a reliable way as much information on Hg coordination as possible. The AmI plants developed more arbuscules and less vesicles than the AmC plants, and also accumulated more Hg in the roots. A clear difference in Hg coordination between the AM (AmC & AmI) and the control (ConC & ConI) plants is recognized in Hg L3-edge EXAFS analysis: in the ConC & ConI maize roots 73–80% of Hg is attached between two sulphur atoms at the distance of 2.34 Å. The remaining ligand is nitrogen at 2.04 Å. In AmI & AmC roots another Hg-S attachment encompassing four thiol groups at the S-distance of 2.50 Å are identified, accounting for 21–26%. AM fungi can modify Hg ligand environment in plant roots, thus playing an important role in biogeochemical cycling of Hg in terrestrial ecosystems.
Found in: osebi
Keywords: EXAFS XANES Arbuscular mycorrhiza Phytoremediation Toxicity Hg coordination Ligand environment
Published: 27.09.2016; Views: 3276; Downloads: 0
.pdf Fulltext (1,82 MB)

Donor doping of K0.5Na0.5NbO3 ceramics with strontium and its implications to grain size, phase composition and crystal structure
Jitka Hreščak, Goran Dražić, Marco Deluca, Iztok Arčon, Alojz Kodre, M. Dapiaggi, Tadej Rojac, Barbara Malič, Andreja Benčan, 2017, original scientific article

Abstract: In this study, the particular effects of A-site donor doping in a lead-free piezoceramic material K0.5Na0.5NbO3 (KNN) doped with Sr2+, i.e., the crystal-structure change, the secondary-phase formation and the grain-size decrease, were investigated. The already-reported causes of these effects upon doping KNN were critically discussed and a mechanism of the effects’ formation was suggested and experimentally supported with advanced analytical methods. Extended X-ray absorption fine structure (EXAFS) analyses proved that the Sr occupies the perovskite A-sublattice, and locally modifies the KNN monoclinic structure to cubic. With the help of Sr K-edge EXAFS and wavelength-dispersive X-ray spectroscopy, the Sr was found to be homogenously distributed in the KNN perovskite lattice with 0.5, 1 and 2% Sr and no Sr segregation on the nano level was found in any of the studied samples with transmission electron microscopy. Introducing Sr into the A-sublattice, as well as accounting for the charge-compensating A-site vacancies in the starting composition, causes increasing lattice disorder and microstrain, as determined from a Rietveld refinement of the synchrotron X-ray diffraction data. Above 2% Sr the system segregates the A-site vacancies in a secondary phase in order to release the chemical pressure, as revealed by Raman spectroscopy. All these effects result in an increasing number of low-angle grain boundaries that limit the grain growth and finally lead to a significant grain-size decrease.
Found in: osebi
Keywords: perovskite, potassium sodium niobate, donor doping, cation vacancies
Published: 17.01.2017; Views: 2502; Downloads: 207
.pdf Fulltext (2,11 MB)

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