Search results for " absorption spectroscopy"
showing 10 items of 293 documents
X-ray absorption spectra at the CaL2,3edge calculated within multichannel multiple scattering theory
2004
We report a theoretical method for x-ray absorption spectroscopy (XAS) in condensed matter which is based on the multichannel multiple scattering theory of Natoli et al. and the eigen-channel $R$-matrix method. While the highly flexible real-space multiple scattering (RSMS) method guarantees a precise description of the single-electron part of the problem, multiplet-like electron correlation effects between the photoelectron and localized electrons can be taken account for in a configuration interaction scheme. For the case where correlation effects are limited to the absorber atom, a technique for the solution of the equations is devised, which requires only little more computation time th…
Element-specific magnetic moments and spin-resolved density of states in CoFeMnZ(Z=Al, Ga; Si, Ge)
2011
Using circular dichroism in x-ray-absorption spectroscopy (XAS/XMCD), we determined element-specific magnetic moments and spin-resolved unoccupied densities of states (DOS) for Co, Fe, and Mn in the quaternary Heusler compounds CoFeMn$Z$ ($Z=\text{Al}$, Ga; Si, Ge). These compounds belong to a class of highly spin-polarized materials with cubic LiMgPdSn-type structure. Different structure models for the sublattice occupation leading to similar average magnetization values can be distinguished by comparison of element-specific moments with theory. We find that the compounds form similar structures, where Co, Fe, Mn, and $Z$ occupy the $X$, ${X}^{\ensuremath{'}}$, $Y$, and $Z$ sublattice of t…
Total Absorption Spectroscopy of Fission Fragments Relevant for Reactor Antineutrino Spectra Determination
2015
8 pags., 3 figs., 1 tab. ; Presented at the XXXIV Mazurian Lakes Conference on Physics, Piaski, Poland, September 6–13, 2015.
Assessment of the quality of the air in the city of Palermo through chemical and cell analyses on Pinus Needles
2001
The influence of air pollution on the chemical composition of Pinus sp. needles was examined in polluted and control sites in and around the city of Palermo (Sicily). The chemical composition of needles indicated the extent of contamination of the trees, which were cytologically examined. Cell analysis was carried out on pine samples, including needles and pollens, from 15 different locations. Biostructural and spectrophotometric tests were performed. In particular, concentrations of toxic (Cd, Pb) and non-toxic metals (Fe,Cu, Zn) were determined, as well as injury caused by their accumulation in the needles. The more highly urbanised areas showed higher concentrations of metals (Pb, Cu. Zn…
Stress-induced cytological and chemical adaptations in Cupressus plants from an urban area of Palermo (Italy)
2004
We studied stress-induced cytological and chemical adaptations in Cupressus pollens and needles from the area of Palermo (Sicily, Italy), in polluted and control sites (unpolluted) of urban and suburban areas. Pollen and needle chemical composition were investigated to provide an indicator of contamination of the trees, which were also examined structurally throughout one year. The concentration of particulate with lead was found to be significantly higher in plants at the polluted traffic site. Lead is one of the worst particulate pollutants in cities, especially in the winter season. In trees from the polluted site, all structural analysis revealed displasies. Structural changes, observed…
Application of algae in active biomonitoring of the selected holding reservoirs in swietokrzyskie province
2016
Abstract During the years 2014-2015, biomonitoring studies were carried out at three holding reservoirs located in Swietokrzyskie Province (central Poland): Kielce artificial lake, Chancza reservoir and Sielpia reservoir. In sea water algae Palmaria palmata (Linnaeus) Weber & Mohr, exposed in the analysed waters, the increases of concentrations were determined by the atomic absorption spectrometry method (AAS), of the following: Mn, Fe, Cu, Zn, Cd and Pb. Conductivity and pH were also determined in the reservoirs waters. The differences between the increases of heavy metal concentrations in the samples of algae found along the coastline were indicated; they result from different distanc…
Cadmium accumulation in the crayfish,Procambarus clarkii, using graphite furnace atomic absorption spectroscopy
1986
Lake Albufera and the surrounding rice-field waters are being subject to very heavy loads of sewage and toxic industrial residues (including heavy metals and pesticides) from the many urban and wastewaters in this area. The American red crayfish Procambarus clarkii is native to the Louisiana marshes (USA). In 1978, the crayfish appeared in Lake Albufera near Valencia (Spain), and presently, without adequate sanitary controls, the crayfish is being fished commercially for human consumption. In view of this interest, it is important to have accurate information on concentrations of cadmium in natural waters and cadmium levels of tissues of freshwaters animals used as human food, as well as th…
Analysis of Mercury Pollution in Air in Urban Area of Riga Using Atomic Absorption Spectrometry
2015
Toxicity of mercury and its compounds is well known, and they are considered as substances of heightened concern. Though mercury is to some extent released into the environment by natural processes such as volcanic eruptions, additional releases from anthropogenic sources have increased the environmental exposure and deposition significantly. There are many commonly used items containing mercury, for instance, mercury light bulbs, switches, and mercury thermometers, the disposal of which into trashcans can cause an increase of mercury concentration in the air of the local area. The paper reports mercury pollution surveys performed in several districts of Riga (the capital of Latvia). Using …
FIA-AAS determination of salicylic acid by a solid-phase reactor of copper carbonate incorporated in polyester resin beads.
1994
Abstract The determination of salicylic acid was carried out by reaction of the drug with copper carbonate entrapped in a polymeric material in a solid-phase reactor; the released cupric ions were monitored by flame atomic absorption at 324.8 nm. The calibration graph is linear over the range 4.0–75 μg ml −1 of salicylic acid, with a relative standard deviation of less than 1.5% and a sample throughout of 257 h −1 . The influence of foreign compounds was studied and the method was applied to the determination of salicylic acid content in two different pharmaceutical formulations.
Chemistry, mineralogy and radioactivity inposidonia oceanicameadows from North-Western Sicily
2004
This paper presents measurements of major, minor, metal trace elements and radionuclides in sediments and in Posidonia oceanica samples from north-western Sicily (Italy). The mineralogical and chemical composition of sediments were determined by X-ray diffraction and X-ray fluorescence techniques, respectively. A flame atomic absorption spectrophotometry was used to measure concentrations of Cu, Zn, Cd and Pb in P. oceanica samples and in sediments. Specific activities of selected radionuclides have been determined by high-resolution gamma spectrometry. Standard statistical analysis was used to assess correlations between different elements and different sample types.