367 research outputs found
Transitions between the -core-excited states in Ir, Ir, and Ir ions for clock applications
Iridium ions near - level crossings are the leading candidates for a
new type of atomic clocks with a high projected accuracy and a very high
sensitivity to the temporal variation of the fine structure constant .
To identify spectra of these ions in experiment accurate calculations of the
spectra and electromagnetic transition probabilities should be performed.
Properties of the -core-excited states in Ir, Ir, and
Ir ions are evaluated using relativistic many-body perturbation theory
and Hartree-Fock-Relativistic method (COWAN code). We evaluate excitation
energies, wavelengths, oscillator strengths, and transition rates. Our
large-scale calculations includes the following set of configurations:
with equal to 3, 2, and 1 for the Ir,
Ir, and Ir ions, respectively. The transitions are
illustrated by the synthetic spectra in the 180 - 200 \AA range. Large
contributions of magnetic-dipole transitions to lifetimes of low-lying states
in the region below 2.5 Ry are demonstrated.Comment: 10 page
Breit Interaction and Parity Non-conservation in Many-Electron Atoms
We present accurate {\em ab initio} non-perturbative calculations of the
Breit correction to the parity non-conserving (PNC) amplitudes of the
and transitions in Cs, and transitions in
Fr, transition in Ba, transition in Ra, and
transition in Tl. The results for the transition
in Cs and transition in Fr are in good agreement with other
calculations while calculations for other atoms/transitions are presented for
the first time. We demonstrate that higher-orders many-body corrections to the
Breit interaction are especially important for the PNC amplitudes. We
confirm good agreement of the PNC measurements for cesium and thallium with the
standard model .Comment: 9 pages, 1 figur
Atomic Properties of Lu
Singly ionised Lutetium has recently been suggested as a potential clock
candidate. Here we report a joint experimental and theoretical investigation of
\ce{Lu^+}. Measurements relevant to practical clock operation are made and
compared to atomic structure calculations. Calculations of scalar and tensor
polarizabilities for clock states over a range of wavelengths are also given.
These results will be useful for future work with this clock candidate.Comment: 12 pages, 5 figure
Excitation energies, hyperfine constants, E1, E2, M1 transition rates, and lifetimes of (6s2)nl states in Tl I and Pb II
Energies of np (n=6-9), ns (n=7-9), nd (n=6-8), and nf (n=5-6) states in Tl I
and Pb II are obtained using relativistic many-body perturbation theory.
Reduced matrix elements, oscillator strengths, transition rates, and lifetimes
are determined for the 72 possible electric-dipole transitions.
Electric-quadrupole and magnetic-dipole matrix elements are evaluated to obtain
np(3/2) - mp(1/2) (n,m=6,7) transition rates. Hyperfine constants A are
evaluated for a number of states in 205Tl. First-, second-, third-, and
all-order corrections to the energies and matrix elements and first- and
second-order Breit corrections to energies are calculated. In our
implementation of the all-order method, single and double excitations of
Dirac-Fock wave functions are included to all orders in perturbation theory.
These calculations provide a theoretical benchmark for comparison with
experiment and theory.Comment: twelve tables, no figure
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