Measurements of the vacuum-ultraviolet (<80-nm) radiation produced by intense ultraviolet (248-nm) irradiation (1015–1016 W/cm2) of rare gases have revealed the copious presence of both harmonic radiation and fluorescence from excited levels. The highest harmonic observed was the seventeenth (14.6 nm) in Ne, the shortest wavelength ever produced by that means. Strong fluorescence was seen from ions of Ar, Kr, and Xe, with the shortest wavelengths observed being below 12 nm. Furthermore, radiation from inner-shell excited configurations in Xe, specifically the 4d95s5p → 4d105s manifold of Xe7+ at ~17.7 nm, was detected. These experimental findings, in alliance with other studies concerning multielectron processes, give evidence for a role of electron correlations in a direct nonlinear process of inner-shell excitation.

Studies of multiphoton production of vacuum-ultraviolet radiation in the rare gases

Resonant Inelastic X-ray Scattering (RIXS)
 is an X-ray in, X-ray out technique that enables one to study the 
dispersion of excitations in solids. In this thesis, we investigated how
 various elementary excitations of transition metal oxides show up in 
RIXS spectra.

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Resonant Inelastic X-ray Scattering Studies of Elementary Excitations

This compilation revises the 1991 listing of atomic data for the lighter elements from hydrogen to gallium. The tabulation emphasizes resonance lines, i.e., lines whose lower level is the ground state, or an excited fine-structure state of the ground term, and is restricted to wavelengths longward of the H I Lyman limit at 911.753 ?. All but the very weakest known and predicted electric-dipole transitions are included, but no forbidden lines. This paper has attempted to review all data published by the end of 2002.?????The tables contain the best data available to the author on ionization potentials, level designations, vacuum and air wavelengths, lower and upper energy levels, statistical weights, transition probabilities, natural damping constants (reciprocal lifetimes), oscillator strengths, and the often used combinations of log gf and log ?f. All ion stages with relevant classified lines are included. Individual components resulting from isotope shift and hyperfine structure are listed explicitly for certain species. The accompanying text provides references, explanations for the critical selection of data, and notes indicating where new measurements or calculations are needed.?????This compilation should be particularly useful in the analysis of interstellar and quasar absorption lines and other astrophysical sites where the density of particles and radiation is low enough to excite only the lowest atomic levels. The data also are relevant to the study of stellar atmospheres, and gaseous nebulae.?????An Appendix summarizes new data relevant to the similar compilation in Paper II for the elements germanium to uranium.

https://iopscience.iop.org/article/10.1086/377639/pdf

Atomic Data for Resonance Absorption Lines. III. Wavelengths Longward of the Lyman Limit for the Elements Hydrogen to Gallium

The grasp2K relativistic atomic structure package

Atomic polarization phenomena impinge upon a number of areas and processes in physics. The dielectric constant and refractive index of any gas are examples of macroscopic properties that are largely determined by the dipole polarizability. When it comes to microscopic phenomena, the existence of alkaline-earth anions and the recently discovered ability of positrons to bind to many atoms are predominantly due to the polarization interaction. An imperfect knowledge of atomic polarizabilities is presently looming as the largest source of uncertainty in the new generation of optical frequency standards. Accurate polarizabilities for the group I and II atoms and ions of the periodic table have recently become available by a variety of techniques. These include refined many-body perturbation theory and coupled-cluster calculations sometimes combined with precise experimental data for selected transitions, microwave spectroscopy of Rydberg atoms and ions, refractive index measurements in microwave cavities, ab initio calculations of atomic structures using explicitly correlated wavefunctions, interferometry with atom beams and velocity changes of laser cooled atoms induced by an electric field. This review examines existing theoretical methods of determining atomic and ionic polarizabilities, and discusses their relevance to various applications with particular emphasis on cold-atom physics and the metrology of atomic frequency standards.

https://iopscience.iop.org/article/10.1088/0953-4075/43/20/202001/pdf

Theory and applications of atomic and ionic polarizabilities

Anisotropy in the beam-foil light source

The 3s23p2 3P-3s3p3 5So intercombination lines in the silicon isoelectronic sequence have been observed for Si I-S III only. By combining ab initio calculations with isoelectronic trend analyses we have obtained predicted values for the 5S2o energy and wavelengths of the intersystem lines in Cl IV-Ni XV. The mixing of the 5S2o level with the triplet levels of the same configuration has been studied in detail. Theoretical results are given for the 5S2o lifetime and the relative intensity of the two intercombination lines. The results are compared with recent MCDF calculations of Huang.

The 3s3p3 5So Level in the Silicon Isoelectronic Sequence

The decay curve of a spectral line with unresolved structure produced by a foil-excited atomic beam is considered in terms of a spherical tensor analysis of the density operator. In the case of L-S coupling, no external field and no cascades, the general expression is displayed and the necessary conditions for the appearance of quantum beats are discussed. By considering a series of special cases, some observable implications of the commonly assumed properties of the beam–foil excitation process are derived.

Density-operator description of foil-excited atomic beams: Zero-field quantum beats in L-S coupling without cascades

The Einstein–Brillouin–Keller semiclassical quantization and the topological Maslov index are used to deduce the correct quantum mechanical values for the energy of a one-electron atom (both nonrelativistically and relativistically) and a three-dimensional harmonic oscillator. The development is concise, transparent, and involves only elementary integral calculus and provides a conceptual and intuitive introduction to the quantum nature of the atomic and molecular structure of matter.

/pdf/use-of-the-einstein-brillouin-keller-action-quantization-2ndcyfvp1p.pdf

Use of the Einstein–Brillouin–Keller action quantization

Highly ionized members of the Pm sequence should produce strong resonance lines in the uv spectra of hot plasmas contaminated by heavy elements. These ions for $Zg~74$ have an alkali structure with ground configuration $4{f}^{14}5s$. Hartree-Fock calculations show that in ${\mathrm{W}}_{\mathrm{XIV}}$ through Uxxxii the dominant resonance lines are the $5s\ensuremath{-}5p$ doublets in the range $\ensuremath{\lambda}=100\ensuremath{-}400$ \AA{}. Approximate predictions are given for the doublet wavelengths, line strengths, and mean lives.

David G. Ellis

Papers

Anisotropy in the beam-foil light source

The 3s3p3 5So Level in the Silicon Isoelectronic Sequence

Density-operator description of foil-excited atomic beams: Zero-field quantum beats in L-S coupling without cascades

Use of the Einstein–Brillouin–Keller action quantization

Alkalilike Spectra in the Promethium Isoelectronic Sequence