680 research outputs found
Formality and Star Products
These notes, based on the mini-course given at the PQR2003 Euroschool held in
Brussels in 2003, aim to review Kontsevich's formality theorem together with
his formula for the star product on a given Poisson manifold. A brief
introduction to the employed mathematical tools and physical motivations is
also given.Comment: 49 pages, 9 figures; proceedings of the PQR2003 Euroschool. Version 2
has minor correction
Relativistic transition wavelenghts and probabilities for spectral lines of Ne II
Transition wavelengths and probabilities for several 2p4 3p - 2p4 3s and 2p4
3d - 2p4 3p lines in fuorine-like neon ion (NeII) have been calculated within
the multiconfiguration Dirac-Fock (MCDF) method with quantum electrodynamics
(QED) corrections. The results are compared with all existing experimental and
theoretical data
QED and relativistic corrections in superheavy elements
In this paper we review the different relativistic and QED contributions to
energies, ionic radii, transition probabilities and Land\'e -factors in
super-heavy elements, with the help of the MultiConfiguration Dirac-Fock method
(MCDF). The effects of taking into account the Breit interaction to all orders
by including it in the self-consistent field process are demonstrated. State of
the art radiative corrections are included in the calculation and discussed. We
also study the non-relativistic limit of MCDF calculation and find that the
non-relativistic offset can be unexpectedly large.Comment: V3, May 31st, 200
Coordinate-space approach to the bound-electron self-energy: Self-Energy screening calculation
The self-energy screening correction is evaluated in a model in which the
effect of the screening electron is represented as a first-order perturbation
of the self energy by an effective potential. The effective potential is the
Coulomb potential of the spherically averaged charge density of the screening
electron. We evaluate the energy shift due to a , ,
, or electron screening a , ,
, or electron, for nuclear charge Z in the range . A detailed comparison with other calculations is made.Comment: 54 pages, 10 figures, 4 table
Determination of selected phthalates by gas chromatography\u2013mass spectrometry in mural paintings from Palermo (Italy)
Phthalate esters for decades, and probably even now, were used as softeners in water-based paintings. In general,
these compounds are dangerous owing to their carcinogenicity and reproductive effects. Phthalates are not
chemically but only physically bound to the matrices, hence, they may be leached into the environment and
are ubiquitously found in environmental matrices. Considering that, construction is one of most important\ufb01elds
in Europe, and probably worldwide, with respect to its economic, technological and environmental impact.
In the present work the phthalate esters content of several mural paintings was evaluated by gas chromatography\u2013
mass spectrometry (GC-MS). Because, this issue is especially important to ensure proper security measurements
during processes that could involve particulate inhalation, the total concentrations of 15 compounds in the analyzed
mural paintings, ranged from 0.8 to 236 mg/Kg d.w. with anaverage of 39.4 mg/Kg d.w. The highest concentration
was found in a mural painting sampled in an apartment built about 50 years ago, though, building age was not
signi\ufb01cantly correlated with the levels of total and single PAEs. Among the monitored phthalates, only four
(bis(2-ethylhexyl) phthalate, diisobutyl phthalate, Di-n-butyl phthalate and diethyl phthalate) were detected in
appreciable quantities. Benzyl butyl phthalate was relevant only for one sample and, at trace levels, only for two
samples. In all tested mural paintings, except two samples, predominates the bis(2-ethylhexyl) phthalate (DEHP)
(from 30 to 100% of total). In general, occasionally, dinonyl phthalate (DNP) was used as an alternative to DEHP,
however, in our case, its occurrence was not found. Diisobutyl phthalate (DiBP) was detected in seven samples
and ranged from 0.17 to 13.2 mg/Kg d.w
Relativistic Calculation of two-Electron one-Photon and Hypersatellite Transition Energies for Elements
Energies of two-electron one-photon transitions from initial double K-hole
states were computed using the Dirac-Fock model. The transition energies of
competing processes, the K hypersatellites, were also computed. The
results are compared to experiment and to other theoretical calculations.Comment: accepted versio
Non-perturbative calculation of the two-loop Lamb shift in Li-like ions
A calculation valid to all orders in the nuclear-strength parameter is
presented for the two-loop Lamb shift, notably for the two-loop self-energy
correction, to the 2p-2s transition energies in heavy Li-like ions. The
calculation removes the largest theoretical uncertainty for these transitions
and yields the first experimental identification of two-loop QED effects in the
region of the strong binding field
Recent Approaches for Chemical Speciation and Analysis by Electrospray Ionization (ESI) Mass Spectrometry
In recent years, the chemical speciation of several species has been increasingly monitored and investigated, employing electrospray ionization mass spectrometry (ESI-MS). This soft ionization technique gently desolvates weak metal\u2013ligand complexes, taking them in the high vacuum sectors of mass spectrometric instrumentation. It is, thus, possible to collect information on their structure, energetics, and fragmentation pathways. For this reason, this technique is frequently chosen in a synergistic approach to investigate competitive ligand exchange-adsorption otherwise analyzed by cathodic stripping voltammetry (CLE-ACSV). ESI-MS analyses require a careful experimental design as measurement may face instrumental artifacts such as ESI adduct formation, fragmentation, and sometimes reduction reactions. Furthermore, ESI source differences of ionization efficiencies among the detected species can be misleading. In this mini-review are collected and critically reported the most recent approaches adopted to mitigate or eliminate these limitations and to show the potential of this analytical technique
QED self-energy contribution to highly-excited atomic states
We present numerical values for the self-energy shifts predicted by QED
(Quantum Electrodynamics) for hydrogenlike ions (nuclear charge ) with an electron in an , 4 or 5 level with high angular momentum
(). Applications include predictions of precision transition
energies and studies of the outer-shell structure of atoms and ions.Comment: 20 pages, 5 figure
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