Related papers: Fine Structure of the 1s3p ^3P_J Level in Atomic ^…
Spectroscopic measurements of the helium atom are performed to high precision using an atomic beam apparatus and electro-optic laser techniques. These measurements, in addition to serving as a test of helium theory, also provide a new…
In order to explain discrepancies between theoretical predictions and experimental data for the helium fine structure, we check and recalculate all theoretical contributions up to orders m\alpha^7 and m^2/M\alpha^6. The previous result for…
Increasing accuracy of the theory and experiment of the $n$$=$$2$ $^3$P fine structure of helium has allowed for increasingly-precise tests of quantum electrodynamics (QED), determinations of the fine-structure constant $\alpha$, and…
The $1\mathrm{s}n\mathrm{p}\,^3\mathrm{P}_J$ fine structure of high Rydberg states in helium has been measured by microwave spectroscopy of single-photon transitions from $1\mathrm{s}n\mathrm{s}\,^3\mathrm{S}_1$ levels in pulsed supersonic…
Improved theoretical predictions for the fine-structure splitting of $2^3P_J$ levels in helium are obtained by the calculation of contributions of order $\alpha^5 Ry$. New results for transition frequencies, $\nu_{01} = 29 616 943.01(17)$…
Calculational results are presented for the fine-structure splitting of the 2^3P state of helium and helium-like ions with the nuclear charge Z up to 10. Theoretical predictions are in agreement with the latest experimental results for the…
The hyperfine constants of the levels 2p2(3P)3s 4P_J, 2p2(3P)3p 4Po_J and 2p2(3P)3p 4Do_J, deduced by Jennerich et al. [Eur. Phys. J. D 40 (2006) 81] from the observed hyperfine structures of the transitions 2p2(3P)3s 4P_J - 2p2(3P)3p…
Configuration interaction in many-electron atoms may cause anomalies in the fine structure which make the intervals small and very sensitive to variation of the fine structure constant. Repeated precision measurements of these intervals…
The unusually large hyperfine structure splittings in the 23P state of the 3He isotope is measured using electro-optic techniques with high precision laser spectroscopy. Originally designed to probe the fine structure of the 4He atom, this…
We critically examine the current status of theoretical calculations of the energies, the fine structure, and the isotope shift of the lowest-lying states of helium, searching for unresolved discrepancies with experiments. Calculations are…
We present recent progress in the calculation of the helium fine-structure splitting of the 2^3P_J states, based on the quantum electrodynamic theory. Apart from the complete evaluation of m\alpha^7 and m^2/M\alpha^6 corrections, we have…
For decades, improved theory and experiment of the $n=2$ $^3$P fine structure of helium have allowed for increasingly-precise tests of quantum electrodynamics, determinations of the fine-structure constant $\alpha$, and limitations on…
The fine structure of the isoscalar giant quadrupole resonance in ^{208}Pb, observed in high-resolution (p,p') and (e,e') experiments, is studied using the entropy index method. In a novel way, it enables to determine the number of scales…
The fine structure interval of P states in hydrogenlike systems can be determined theoretically with high precision, because the energy levels of P states are only slightly influenced by the structure of the nucleus. Therefore a measurement…
We review the status of the QED calculations for the muonium $2S_{1/2}-2P_{3/2}$ energy interval and provide the updated theoretical value of $9874.357\pm0.001\,\mathrm{MHz}$. Additionally, we present a model for probing Lorentz-violating…
Large-scale {\em ab initio} QED calculations are performed for the $2p_{3/2}$--$2p_{1/2}$ fine-structure interval of Li-like ions with nuclear charges $Z = 5\,$--$\,92$. Improved theoretical predictions are obtained by combining together…
Using relativistic multiconfiguration Dirac-Hartree-Fock method, we calculate the hyperfine-structure properties of the $2s2p$ $^3\!P_{J}$ state in $^9$Be. The hyperfine-structure properties encompass first-order hyperfine-structure…
We demonstrate a technique for directly measuring the fine-structure interval in alkali atoms using two frequency-stabilized diode lasers. Each laser has a linewidth of order 1 MHz and precise tunability: one laser is tuned to a hyperfine…
We report measurements of the hyperfine coupling constant for the $8p \ ^2P_{1/2}$ level of atomic cesium, $^{133}$Cs, with a relative uncertainty of $\sim$0.019\%. Our result is $A = 42.933 \: (8)$ MHz, in good agreement with recent…
Motivated by the recent experimental measures of the 2p-states fine splitting of the muonic He4 ion [1], we think it may have some interest to present an independent calculation in terms of the two-body relativistic equation for a scalar…