Search results for "absorption spectroscopy"
showing 10 items of 828 documents
Volcanic CO2 flux measurement at Campi Flegrei by tunable diode laser absorption spectroscopy
2014
Near-infrared room-temperature Tunable Diode Lasers (TDL) have recently found increased usage in atmospheric chemistry and air monitoring research, but applications in volcanology are still limited to a few examples. Here, we explored the potential of a commercial infrared laser unit (GasFinder 2.0 from Boreal Laser Ltd) for measurement of volcanic CO2 mixing ratios, and ultimately for estimating the volcanic CO2 flux. Our field tests were conducted at Campi Flegrei near Pozzuoli, Southern Italy, where the GasFinder was used during three campaigns in October 2012, January 2013 and May 2013 to repeatedly measure the path-integrated mixing ratios of CO2 along cross-sections of the atmospheric…
Modelling molecular iodine emissions in a coastal marine environment: The link to new particle formation
2006
International audience; A model of iodine chemistry in the marine boundary layer (MBL) has been used to investigate the impact of daytime coastal emissions of molecular iodine (I2). The model contains a full treatment of gas-phase iodine chemistry, combined with a description of the nucleation and growth, by condensation and coagulation, of iodine oxide nano-particles. In-situ measurements of coastal emissions of I2 made by the broadband cavity ring-down spectroscopy (BBCRDS) and inductively coupled plasma-mass spectrometry (ICP/MS) techniques are presented and compared to long path differential optical absorption spectroscopy (DOAS) observations of I2 at Mace Head, Ireland. Simultaneous me…
Surfactant-assisted synthesis of Cd1−xCoxS nanocluster alloys and their structural, optical and magnetic properties
2010
We report the synthesis of Co-doped CdS nanoclusters (Cd1−xCoxS) for different doping concentrations (x = 0.10, 0.20 and 0.30) and characterization of their structural, optical, and magnetic properties. The structural properties studied by X-ray diffraction revealed hexagonal-greenockite structure and a decrease of the lattice parameters (a and c) with doping, showing incorporation of Co in the lattice. The morphology of the nanoclusters was studied by scanning electron microscopy. The optical absorption studies, using diffused reflectance spectroscopy, revealed that Co doping modifies the absorption band edge. Ferromagnetic phase was observed in the magnetization measurements at room-tempe…
The arsenic content of human semen.
2009
Arsenic concentration was measured by atomic absorption spectrometer in ejaculates of 13 subfertile men, 6 control individuals and pool-ejaculate of 24 further andrological patients. While the detection limit was 1 microgram/l, arsenic concentration amounted to 2 micrograms AS/l in ejaculates. In the cellular fractions of seminal fluid, concentration of arsenic was under the detection limit. Arsenic concentration of smokers and non-smokers did not differ.
Comparison of ultrasound-assisted extraction, microwave-assisted acid leaching and reflux for the determination of arsenic, cadmium and copper in con…
2002
Extraction methods for the determination of arsenic, cadmium, and copper in contaminated soil samples by Zeeman effect electrothermal atomic absorption spectrometry have been compared. The determination of cadmium and copper in ultrasound-assisted aqua regia extracts of contaminated soil SRMs by ETAAS, using a mixture of NH4H2PO4 and Mg(NO3)2, for cadmium, and a mixture of Pd and Mg(NO3)2, for copper, as a matrix modifier, was carried out with high accuracy and precision (RSD < 5.1%). The analysis of SRM 2711 failed to obtain the certified concentrations of Cd and Cu by microwave and reflux methods, respectively. The determination of arsenic was performed successfully in low chloride concen…
Determination of Cd, Co, Cu, Fe, Pb, Mn, Ni and Zn in diets: Development of a method
1991
A method useful for the determination of cadmium, cobalt, copper, iron, lead, manganese, nickel and zinc in diets is described. Organic matter is destroyed applying a wet procedure, and element content is measured by flame atomic absorption spectroscopy (FAAS) in the case of copper, iron, manganese, nickel and zinc, and by graphite furnace (GF-AAS) in the case of cadmium, cobalt and lead. The matrix interference study is carried out. Values found for linearity, detection and quantitation limits as well as accuracy show that the described method is useful to determine the elements taken into account at usual levels in diets.
Determination of selenium, zinc and cadmium in antidandruff shampoos by atomic spectrometry after microwave assisted sample digestion
2000
Microwave assisted pre-treatments for atomic spectrometric determination (inductive coupled plasma-optical emission spectrometry, ICP-OES or flame atomic absorption spectrometry, FAAS) of metallic elements, usually present in antidandruff shampoos, are proposed. They are based on the digestion of the sample with HNO(3) into a closed reactor, which is irradiated at 800 W for a few minutes. Selenium was determined by ICP-OES. The limit of detection was 0.11 mg l(-1); the relative standard deviation (R.S.D.) for the selenium content in the samples was in the 0.6-3.6% range. The results obtained were in agreement with the label contents and the recovery of the proposed method was in the 100-106…
Electrothermal Atomic Absorption Determination of Chromium in Sediments
1999
Abstract An electrothermal atomic absorption spectrometric method has been developed to determine total chromium concentration in natural sediment samples. Samples were mineralized by dry ashing at 550°C and fused at 1100°C for 30 min with lithium metaborate. Dissolved samples were injected in graphite tubes, mineralized at 1100°C, and atomized at 2600°C. Standard addition calibration made unnecessary the use of chemical modifiers. The method provided a limit of detection from 23 to 45 ng liter −1 . The relative standard deviation for chromium determination was between 3 and 14%. Results obtained for a standard reference material agree well with the certified value. A series of natural samp…
Optical Properties of Natural and Synthetic Minerals
2015
The results of investigation of optical absorption and photoluminescence (PL) of topaz, beryl and yttrium aluminium garnet crystals doped with different concentrations of transition ions exposed to fast neutron irradiation and electron irradiation are presented. We suppose that irradiation leads to the formation of two types of complex centers: "Me2+-F+ (or F) centre" and complex centers, which consist of a cation vacancy and an impurity (iron, manganese and chromium) ion. Exchange interaction between radiation defects and impurity ions during neutron or electron irradiation gives rise to appearance of additional absorption and luminescence band broadening in investigated crystals.
Evaluation of Antimony, Cadmium and Lead Levels in Vegetables, Drinking and Raw Water from Different Agricultural Areas
1990
Abstract Lead and cadmium levels in edible vegetables and antimony, lead and cadmium in drinking and raw waters from three agricultural areas exposed to different levels of environmental pollution (1-high industrial pollution, 2-high urban pollution, 3-standard low industrial and urban pollution) are determined. The organic matter is destroyed by repeated attack with nitric acid. Cadmium and lead are determined by graphite furnace atomic absorption spectrometry (GFAAS) and antimony by hydride generation atomic absorption spectrometry (HGAAS). When the results obtained for three different areas are compared, differences between cadmium and lead contents in vegetables are observed. Waters are…