Environment assisted electron capture

Electron capture by {\it isolated} atoms and ions proceeds by photorecombination. In this process a species captures a free electron by emitting a photon which carries away the excess energy. It is shown here that in the presence of an {\it environment} a competing non-radiative electron capture process can take place due to long range electron correlation. In this interatomic (intermolecular) process the excess energy is transferred to neighboring species. The asymptotic expression for the cross section of this process is derived. We demonstrate by explicit examples that under realizable conditions the cross section of this interatomic process can clearly dominate that of photorecombination

Chemi-ionization in Solar Photosphere: Influence on the Hydrogen Atom excited States Population

In this paper, the influence of chemi-ionization processes in $H^*(n \ge 2) + H(1s)$ collisions, as well as the influence of inverse chemi-recombination processes on hydrogen atom excited-state populations in solar photosphere, are compared with the influence of concurrent electron-atom and electron-ion ionization and recombination processes. It has been found that the considered chemi-ionization/recombination processes dominate over the relevant concurrent processes in almost the whole solar photosphere. Thus, it is shown that these processes and their importance for the non-LTE modeling of the solar atmosphere should be investigated further

Bound state properties of four-body muonic quasi-atoms

Total energies and various bound state properties are determined for the ground states in all six four-body muonic $a^{+} b^{+} \mu^{-} e^{-}$ quasi-atoms. These quasi-atoms contain two nuclei of the hydrogen isotopes $p^{+}, d^{+}, t^{+}$, one negatively charged muon $\mu^{-}$ and one electron $e^{-}$. In general, each of the four-body muonic $a^{+} b^{+} \mu^{-} e^{-}$ quasi-atoms, where $(a, b) = (p, d, t)$, can be considered as the regular one-electron (hydrogen) atom with the complex nucleus $a^{+} b^{+} \mu^{-}$ which has a finite number of bound states. Furthermore, all properties of such quasi-nuclei $a^{+} b^{+} \mu^{-}$ are determined from highly accurate computations performed for the three-body muonic ions $a^{+} b^{+} \mu^{-}$ with the use of pure Coulomb interaction potentials between particles. It is shown that the bound state spectra of such quasi-atoms are similar to the spectrum of the regular hydrogen atoms, but there are a few important differences. Such differences can be used in future experiments to improve the overall accuracy of current evaluations of various properties of hydrogen-like systems, including the lowest-order relativistic and QED corrections

Interaction of photons with plasmas and liquid metals: photoabsorption and scattering

Formulas to describe the photoabsorption and the photon scattering by a plasma or a liquid metal are derived in a unified manner with each other. It is shown how the nuclear motion, the free-electron motion and the core-electron behaviour in each ion in the system determine the structure of photoabsorption and scattering in an electron-ion mixture. The absorption cross section in the dipole approximation consists of three terms which represent the absorption caused by the nuclear motion, the absorption owing to the free-electron motion producing optical conductivity or inverse Bremsstrahlung, and the absorption ascribed to the core-electron behaviour in each ion with the Doppler correction. Also, the photon scattering formula provides an analysis method for experiments observing the ion-ion dynamical structure factor (DSF), the electron-electron DSF giving plasma oscillations, and the core-electron DSF yielding the X-ray Raman (Compton) scattering with a clear definition of the background scattering for each experiment, in a unified manner. A formula for anomalous X-ray scattering is also derived for a liquid metal. At the same time, Thomson scattering in plasma physics is discussed from this general point of view.Comment: LaTeX file: 18 pages without figur

Relativistic nuclear recoil corrections to the energy levels of hydrogen-like and high ZZ lithium like atoms in all orders in αZ\alpha Z

The relativistic nuclear recoil corrections to the energy levels of low-laying states of hydrogen-like and high $Z$ lithium-like atoms in all orders in $\alpha Z$ are calculated. The calculations are carried out using the B-spline method for the Dirac equation. For low $Z$ the results of the calculation are in good agreement with the $\alpha Z$ -expansion results. It is found that the nuclear recoil contribution, additional to the Salpeter's one, to the Lamb shift ($n=2$) of hydrogen is $-1.32(6)\,kHz$. The total nuclear recoil correction to the energy of the $(1s)^{2}2p_{\frac{1}{2}}-(1s)^{2}2s$ transition in lithium-like uranium constitutes $-0.07\,eV$ and is largely made up of QED contributions.Comment: 19 pages, latex, accepted for publication in Phys. Rev.

Transition probabilities of 30 Pb II lines of spectrum obtained by emission of a laser-produced plasma

Transition probabilities have been determined for 30 lines of Pb II by measuring the intensities of the emission lines of a laser-produced plasma (LPP) of Pb in an atmosphere of Ar. The plasma has been seen to contain local thermodynamic equilibrium (LTE) and homogeneity; the plasma studied has a temperature of 11 500 K and an electron density of 1016 cm−3. The experimental results obtained during this study have been compared with the experimental and theoretical values given by other authors

Irreducible tensor-form of the relativistic corrections to the M1 transition operator

The relativistic corrections to the magnetic dipole moment operator in the Pauli approximation were derived originally by Drake (Phys. Rev. A 3(1971)908). In the present paper, we derive their irreducible tensor-operator form to be used in atomic structure codes adopting the Fano-Racah-Wigner algebra for calculating its matrix elements.Comment: 26 page