Search results for "Spectrometry"
showing 10 items of 3206 documents
Analytical Study of a Resinous Material Used as Sealing in Ancient Pottery Found in an Archaeological Site by Thermally Assisted Hydrolysis Methylati…
2009
Abstract A resin sample was found in the archaeological site of Lixus (Morocco), belonging to the second century BC. The resinous material was found inside an amphora containing iron remains used in the plug as sealing material to hermetically close the pottery. The resinous sample was studied by several analytical techniques, as thermally assisted hydrolysis and methylation–gas chromatography–mass spectrometry (THM–GC–MS), Fourier transformed infrared spectroscopy (FTIR), and light microscopy. The material was identified as a Pinaceae resin. Therefore, a modern pine resin was also analyzed to consider the influence of aging in the archaeological sample. The ancient material was found not t…
Fourier transform infrared analysis of paint solvents
1991
Abstract The composition of solvent mixtures employed in the paint industry was determined by Fourier transform infrared spectrometry. A procedure based on the use of the ratio between the absorbance of characteristic bands of each component permits the ratio between two solvents in a binary mixture to be determined, independently of the thickness of the sample film. Typical mixtures of xylol with butan-1-ol and with butyl acetate (xylol=mixture of o-, m- and p-xylenes) were used as model systems to develop the proposed procedure and the accuracy was determined using synthetic formulations. Another possible application of the procedure is the characterization of azeotropic mixtures.
CASSCF/CASPT2 analysis of the fragmentation of H2 on a Pd4 cluster
2009
Two reactive pathways are described for the dissociative adsorption of a hydrogen molecule on a Pd4 pyramidal cluster, by using DFT/B3LYP and CASSCF/CASPT2 computational methods. Because of the different spin multiplicities of the cluster in the initial and final states, the reaction proceeds through a spin multiplicity change, which occurs close to the transition states. The activation energy values are very similar when the DFT method is used, whereas the CASPT2 calculations predict that the concerted mechanism is disfavored. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
Excitation modes for fourier transform-ion cyclotron resonance mass spectrometry.
1992
AbstractVarious geometric configurations for the excitation of coherent ion motion in Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR/MS) are analyzed (in some cases for the first time) with unified notation. The instantaneous power absorption, F·v, in which v is ion velocity and F the force produced by the applied excitation electric field (harmonic, single frequency, on-resonance, in-phase), is time averaged and then set equal to the time rate of change of ion total (cyclotron + magnetron + trapping) energy, to yield a differential equation that is readily solved for the (time-dependent) amplitude of each of the various ion motions. The standard FT-ICR excitation (name…
Theory of quadrupole detection fourier transform-ion cyclotron resonance
1991
Abstract The theoretical basis of the recently introduced quadrupole detection Fourier transform-ion cyclotron resonance technique is developed by use of the concept of image charges induced in the detection electrodes. The appearance of resonances at frequencies 2ω+, 2ω−, (ω+ + ω−) and (ω+ − ω−) is explained. The new method is compared with the standard (dipole) detection scheme. Techniques are suggested allowing the simultaneous determination of all resonance frequencies ω+ (perturbed, or reduced, cyclotron frequency), ω− (magnetron frequency) and ωz (trapping frequency).
Damping effects in Penning trap mass spectrometry
2011
Abstract Collisions of ions with residual gas atoms in a Penning trap can have a strong influence on the trajectories of the ions, depending on the atom species and the gas pressure. We report on investigations of damping effects in time-of-flight ion-cyclotron resonance mass spectrometry with the Penning trap mass spectrometers ISOLTRAP at ISOLDE/CERN (Geneva, Switzerland) and SHIPTRAP at GSI (Darmstadt, Germany). The work focuses on the interconversion of the magnetron and cyclotron motional modes, in particular the modification of the resonance profiles for quadrupolar excitation due to the damping effect of the residual gas. Extensive experiments have been performed with standard and Ra…
FeMnOx-1: A new microanalytical reference material for the investigation of Mn–Fe rich geological samples
2016
Suitable Mn-Fe rich microanalytical reference materials (MRMs) as calibration material for laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) have not been available. The United States Geological Survey (USGS) in collaboration with the Max Planck Institute for Chemistry has prepared a synthetic MRM, FeMnOx-1, with elevated mass fractions of MnO (25 g/100 g), Fe2O3 (8.5 g/100 g) and high mass fractions of 25 trace elements varying between 200 and 5000 mg/kg. This new MRM has been designed as calibration material for a wide range of different Mn-Fe deposits, such as desert/rock varnish, ocean crusts and nodules as well as Mn accumulations in soils and lakes. Small-scale an…
Micro-analytical identification of the components of varnishes from South Italian historical musical instruments by PLM, ESEM-EDX, microFTIR, GC-MS, …
2014
Abstract A multi-analytical investigation was carried out to study varnish micro-samples from historical stringed musical instruments from the collection of the “Vincenzo Bellini” Conservatory in Palermo (Italy). This paper reports on the results of the application of five micro-destructive techniques: optical microscopy analysis of cross-sections, micro-Fourier transform infrared spectroscopy, gas chromatography coupled with mass spectrometry, pyrolysis gas chromatography coupled with mass spectrometry with thermochemolysis, and environmental scanning electron microscopy with X-ray microanalysis. The study provides microchemical information about the composition of the varnishes of the ins…
Cooperatively Enhanced Ion Pair Binding with a Hybrid Receptor
2015
A simple 18-crown-6-based bis-urea receptor R(1) was synthesized in three steps from a commercial starting material. The receptor's behavior toward anions, cations, and ion pairs was studied in solution with (1)H NMR, in solid state with single-crystal X-ray diffraction, and in gas phase with mass spectrometry. In 4:1 CDCl3/dimethyl sulfoxide solution the receptor's binding preference of halide anions is I(-) < Br(-) < Cl(-) following the trend of the hydrogen-bonding acceptor ability of the anions. The receptor shows a remarkable positive cooperativity toward halide anions Cl(-), Br(-), and I(-) when complexed with Na(+), K(+), or Rb(+). The solid-state binding modes of R(1) with alkali an…
EDXRF and TXRF analysis of elemental size distributions and environmental mobility of airborne particles in the city of Riga, Latvia
2004
Airborne particles were investigated in the central part of Riga during October 2000. Mass, black carbon and elemental concentrations of airborne particles were measured on Teflon filters from a dichotomous impactor, which samples fine (<2.5 µm) and coarse (2.5‐10 µm) fractions of particles. In order to obtain more detailed information on the size distributions of different elements, a seven-stage Batelle cascade impactor was used, in which quartz plates treated with silicone grease were utilized as backing for the different stages. Total reflection x-ray fluorescence (TXRF) and energy-dispersive x-ray fluorescence (EDXRF) spectrometry were used for elemental analysis on the quartz plates a…