75 research outputs found
Finite nuclear size correction to the bound-electron g factor in a hydrogenlike atom
The finite nuclear size correction to the bound-electron g factor in
hydrogenlike atoms is investigated in the range Z=1-20. An analytical formula
for this correction which includes the non-relativistic and dominant
relativistic contributions is derived. In the case of the 1s state, the results
obtained by this formula are compared with previous non-relativistic analytical
and relativistic numerical calculations.Comment: 5 page
Magnetic moment of the two-particle bound state in quantum electrodynamics
We have formulated the quasipotential method for the calculation of the
relativistic and radiative corrections to the magnetic moment of the
two-particle bound state in the case of particles with arbitrary spin. It is
shown that the g-factors of bound particles contain terms
depending on the particle spin. Numerical values for the g-factors of the
electron in the hydrogen atom and deuterium are obtained.Comment: Talk presented at Nuclear Physics Department Conference "Physics of
Fundamental Interactions" Russian Academy of Sciences, ITEP, Moscow, 27
November-1 December 2000. 11 pages, 1 figure uses linedraw.st
QED theory of the nuclear recoil effect on the atomic g factor
The quantum electrodynamic theory of the nuclear recoil effect on the atomic
g factor to all orders in \alpha Z and to first order in m/M is formulated. The
complete \alpha Z-dependence formula for the recoil correction to the
bound-electron g factor in a hydrogenlike atom is derived. This formula is used
to calculate the recoil correction to the bound-electron g factor in the order
(\alpha Z)^2 m/M for an arbitrary state of a hydrogenlike atom.Comment: 17 page
g factor of Li-like ions with nonzero nuclear spin
The fully relativistic theory of the g factor of Li-like ions with nonzero
nuclear spin is considered for the (1s)^2 2s state. The magnetic-dipole
hyperfine-interaction correction to the atomic g factor is calculated including
the one-electron contributions as well as the interelectronic-interaction
effects of order 1/Z. This correction is combined with the
interelectronic-interaction, QED, nuclear recoil, and nuclear size corrections
to obtain high-precision theoretical values for the g factor of Li-like ions
with nonzero nuclear spin. The results can be used for a precise determination
of nuclear magnetic moments from g factor experiments.Comment: 20 pages, 5 figure
QED Effects in Heavy Few-Electron Ions
Accurate calculations of the binding energies, the hyperfine splitting, the
bound-electron g-factor, and the parity nonconservation effects in heavy
few-electron ions are considered. The calculations include the relativistic,
quantum electrodynamic (QED), electron-correlation, and nuclear effects. The
theoretical results are compared with available experimental data. A special
attention is focused on tests of QED in a strong Coulomb field.Comment: 28 pages, 6 tables, 5 figure
Recoil correction to the bound-electron g factor in H-like atoms to all orders in
The nuclear recoil correction to the bound-electron g factor in H-like atoms
is calculated to first order in and to all orders in . The
calculation is performed in the range Z=1-100. A large contribution of terms of
order and higher is found. Even for hydrogen, the higher-order
correction exceeds the term, while for uranium it is above the
leading correction.Comment: 6 pages, 3 tables, 1 figur
Trapped electron coupled to superconducting devices
We propose to couple a trapped single electron to superconducting structures
located at a variable distance from the electron. The electron is captured in a
cryogenic Penning trap using electric fields and a static magnetic field in the
Tesla range. Measurements on the electron will allow investigating the
properties of the superconductor such as vortex structure, damping and
decoherence. We propose to couple a superconducting microwave resonator to the
electron in order to realize a circuit QED-like experiment, as well as to
couple superconducting Josephson junctions or superconducting quantum
interferometers (SQUIDs) to the electron. The electron may also be coupled to a
vortex which is situated in a double well potential, realized by nearby pinning
centers in the superconductor, acting as a quantum mechanical two level system
that can be controlled by a transport current tilting the double well
potential. When the vortex is trapped in the interferometer arms of a SQUID,
this would allow its detection both by the SQUID and by the electron.Comment: 13 pages, 5 figure
Nanofriction in Cold Ion Traps
Sliding friction between crystal lattices and the physics of cold ion traps
are so far non-overlapping fields. Two sliding lattices may either stick and
show static friction or slip with dynamic friction; cold ions are known to form
static chains, helices, or clusters, depending on trapping conditions. Here we
show, based on simulations, that much could be learnt about friction by
sliding, via e.g. an electric field, the trapped ion chains over a periodic
corrugated potential. Unlike infinite chains where, according to theory, the
classic Aubry transition to free sliding may take place, trapped chains are
always pinned. Nonetheless we find that a properly defined static friction
still vanishes Aubry-like at a symmetric-asymmetric structural transition,
ubiquitous for decreasing corrugation in both straight and zig-zag trapped
chains. Dynamic friction can also be addressed by ringdown oscillations of the
ion trap. Long theorized static and dynamic one dimensional friction phenomena
could thus become exquisitely accessible in future cold ion tribology
Two-time Green function method in quantum electrodynamics of high-Z few-electron atoms
The two-time Green function method in quantum electrodynamics of high-Z
few-electron atoms is described in detail. This method provides a simple
procedure for deriving formulas for the energy shift of a single level and for
the energies and wave functions of degenerate and quasi-degenerate states. It
also allows one to derive formulas for the transition and scattering
amplitudes. Application of the method to resonance scattering processes yields
a systematic theory for the spectral line shape. The practical ability of the
method is demonstrated by deriving formulas for the QED and
interelectronic-interaction corrections to energy levels and transition and
scattering amplitudes in one-, two-, and three-electron atoms. Numerical
calculations of the Lamb shift, the hyperfine splitting, the bound-electron g
factor, and the radiative recombination cross section in heavy ions are also
reviewed.Comment: 92 pages, 39 figures, 7 table
Synthesis of functionalised supramolecular assemblies.
This thesis features supramolecular assemblies that have functional groups incorporated into them, with the intention of introducing the properties of these functional moieties into the supramolecular structure. The functionalities investigated included squaramide, pyrene and tribenzylamine moieties each possessing unique properties discussed further below. The ligands synthesised in this thesis were designed to produce discrete supramolecular architectures through the inclusion of converging metal binding sites. The formation of the resulting supramolecular assemblies was investigated through both solid and solution state analyses.
In chapter 2, the incorporation of squaramide moieties into discrete supramolecular assemblies, through the design of flexible and rigid squaramide-based ligands, is presented. The flexible squaramide ligands created metallo-supramolecular triple-stranded helicates through various sub-component self-assembly of pro-ligands, metal ions and aldehyde ‘head groups’, which were characterised through ESI-MS. The rigid squaramide ligands formed tetrahedral [M₄L₆]⁸⁺ cages, as observed through X-ray crystallography and, upon modification of the ligand to improve solubility, complexometric UV-Vis and ¹H-NMR experiments were conducted. The host-guest capability of these discrete structures was investigated through NMR experiments, however, no signal associated with guest encapsulation was observed due to either guest exchange occurring faster than the NMR timescale or the large aperture size of the cages failing to capture the guest. The inherent guest binding properties of the squaramide nitro precursors against a series of anions were independently investigated through guest binding studies which followed trends reported in the literature.
Chapter 3 investigated the pyrene moiety embedded within supramolecular assemblies, with metal ions of different geometries resulting in either cubic [M₈L₆]¹⁶⁺ cages or dimeric [M₄L₂]⁸⁺ stacks. Solution state UV-Vis complexometric titrations confirmed the formation of both species in the solution. The emission properties of both species were investigated at the beginning and end of the complexometric titrations to observe whether the luminescent properties of pyrene were translated into the supramolecular structures. For the cubic cages, no emission was observed after the formation of the cage, however, the dimeric stack retained the luminescent properties of the ligand after complexation.
Chapter 4 discusses the supramolecular assemblies formed with the tribenzylamine precursor featuring salicylimine or 2-pyrrolyimine ‘head groups’ and subsequent investigations through UV-Vis complexometric titration studies. These ‘head groups’ require deprotonation before complexation which was achieved through either utilisation of basic acetate metal salts or the addition of triethylamine to the titration. The salicylimine ‘head group’ resulted in the formation of [M₃L₂] neutral complexes, with the zinc complex exhibiting luminescence. The pyrrolimine ‘head group’ led to the formation of a 1:1 ratio product forming which could be either a double-stranded helicate, molecular triangle or molecular square.
Chapter 5 concludes the thesis and presents some future work and Chapter 6 details the experimental procedures
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