Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userRelativistic Calculation of two-Electron one-Photon and Hypersatellite Transition Energies for $12leq Zleq30$ Elements
100
0
0.0
(
0
)
Added by
Docteur Paul Indelicato
Publication date
2004
fields
Physics
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
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$alpha$ hypersatellites, were also computed. The results are compared to experiment and to other theoretical calculations.
rate research
Read More
A new mechanism of nuclear excitation via two-photon electron transitions (NETP) is proposed and studied theoretically. As a generic example, detailed calculations are performed for the $E1E1$ $1s2s,^1S_0 rightarrow 1s^2,^1S_0$ two-photon decay of He-like $^{225}$Ac$^{87+}$ ion with the resonant excitation of the $3/2+$ nuclear state with the energy 40.09(5) keV. The probability for such a two-photon decay via the nuclear excitation is found to be $P_{rm NETP} = 3.5 times 10^{-9}$ and, thus, is comparable with other mechanisms, such as nuclear excitation by electron transition and by electron capture. The possibility for the experimental observation of the proposed mechanism is thoroughly discussed.
The ground-state energies of one-electron homonuclear quasi-molecules for the nuclear charge number in the range Z=1-100 at the chemical distances R= 2/Z (in a.u.) are calculated. The calculations are performed for both point- and extended-charge nucleus cases using the Dirac-Fock-Sturm approach with the basis functions constructed from the one-center Dirac-Sturm orbitals. The critical distances R_cr, at which the ground-state level reaches the edge of the negative-energy Dirac continuum, are calculated for homonuclear quasi-molecules in the range: Z=85-100. It is found that in case of U_2^{183+} the critical distance R_cr = 38.42 fm for the point-charge nuclei and R_cr = 34.72 fm for extended nuclei.
We resonantly excite the $K$ series of O$^{5+}$ and O$^{6+}$ up to principal quantum number $n=11$ with monochromatic x rays, producing $K$-shell holes, and observe their relaxation by soft-x-ray emission. Some photoabsorption resonances of O$^{5+}$ reveal strong two-electron--one-photon (TEOP) transitions. We find that for the $[(1s,2s)_1,5p_{3/2}]_{3/2;1/2}$ states, TEOP relaxation is by far stronger than the radiative decay and competes with the usually much faster Auger decay path. This enhanced TEOP decay arises from a strong correlation with the near-degenerate upper states $[(1s,2p_{3/2})_1,4s]_{3/2;1/2}$ of a Li-like satellite blend of the He-like $Kalpha$ transition. Even in three-electron systems, TEOP transitions can play a dominant role, and the present results should guide further research on the ubiquitous and abundant many-electron ions where electronic energy degeneracies are far more common and configuration mixing is stronger.
The low-energy electron spectra emitted in the radioactive decay of the $^{83}$Rb and $^{83}$Sr isotopes were measured with a combined electrostatic electron spectrometer. Radioactive sources used were prepared by ion implantation of $^{83}$Sr into a high purity polycrystalline platinum foil at 30 keV and by vacuum-evaporation deposition of $^{83}$ Rb on the same type of foil. From the measured conversion electron spectra, the electron binding energies (referenced to the Fermi level) for the K, L$_1$ , L$_2$ , L$_3$ , M$_1$ , M$_2$, and M$_3$ shell/subshells of krypton in the platinum host were determined to be 14 316.4(12), 1 914.3(9), 1 720.3(9), 1 667.6(9), 281.5(9), 209.6(13), and 201.2(15) eV, respectively, and those for the evaporated layer were observed to be lower by 0.7(1) eV. For both host matrices, values of 2.3(2), 4.6(2), 1.7(2), 1.3(2), and 3.2(3) eV were obtained for the krypton K, L$_1$ , L$_2$ , L$_3$ , and M$_1$ natural atomic level widths, respectively. The absolute energies of 10 838.5(9) and 10 839.5(10) eV were measured for the KL$_2$L$_3$ ($^{1}$D$_2$) Auger transition in krypton implanted in Pt and generated in the evaporated rubidium layer, respectively. A value of 601.0(8) eV was measured for the energy difference of the KL$_2$L$_3$ ($^{1}$D$_2$) transitions in Rb and Kr in the Pt host. Multiconfiguration Dirac-Fock calculations of the krypton KLL transition energies and intensities were also performed.
Energy levels of 30 low-lying states of Lu2+ and allowed electric-dipole matrix elements between these states are evaluated using a relativistic all-order method in which all single, double and partial triple excitations of Dirac-Fock wave functions are included to all orders of perturbation theory. Matrix elements are critically evaluated for their accuracy and recommended values of the matrix elements are given together with uncertainty estimates. Line strengths, transition rates and lifetimes of the metastable 5d(3/2) and 5d(5/2) states are calculated. Recommended values are given for static polarizabilities of the 6s, 5d and 6p states and tensor polarizabilities of the 5d and 6p(3/2) states. Uncertainties of the polarizability values are estimated in all cases. The blackbody radiation shift of the 6s(1/2)-5d(5/2) transition frequency of the Lu2+ ion is calculated with the aid of the recommended scalar polarizabilities of the 6s(1/2) and 5d(5/2) states. Finally, A and B hyperfine constants are determined for states of 175Lu2+ with n <= 9. This work provides recommended values of transition matrix elements, polarizabilities and hyperfine constants of Lu2+, critically evaluated for accuracy, for benchmark tests of high-precision theoretical methodology and planning of future experiments.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
