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A multitude of weaker Fe IX lines have been predicted in the vicinity of the strong 171 Å line that dominates the spectra of many astrophysical and laboratory sources. Some of these weaker lines have only recently been identified in the laboratory, albeit some only tentatively. Here, we present measurements on the Livermore EBIT-I electron beam ion trap that span the region from 170.0 to 173.6 Å, which surrounds the 171 Å line. The measurements stepped through electron beam energy to determine the charge state of iron associated with each observed feature. Moreover, we have minimized the presence of oxygen in the trap, because oxygen lines obscured possible Fe IX lines in past measurements and prevented their identification. Our measurement confirms formerly tentative identifications and adds several new assignments.

Based on the two-fluid model of helium II, a theory is proposed to explain the recently observed temperature dependence of the zero-phonon line (ZPL) in the optical spectra of Dy atoms in superfluid helium. According to this theory, the main reason for the observed dependence is the temperature redistribution of the normal and superfluid components of the liquid helium. It is also found that due to the Archimedes' principle, the linear vibronic interaction with long-wave phonons in the liquid phase is singularly enhanced. This enhancement, in turn, leads to a finite broadening of the ZPL of the superfluid component and a linear temperature dependence of the ZPL width of the normal component. The proposed theory allows us to explain the experimental results.

Agradecimentos: We are very grateful to Fausto Bredice, who helped us in the preliminary discussions. This research was supported by the Consejo Nacional de Investigaciones Científicas y Tecnicas (CONICET), Argentina, and by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Brazil, Finance Code 001. The support from the Comision de Investigaciones Científicas de la Província de Buenos Aires (CIC), where M.R. and J.R.A. are researchers, is gratefully acknowledged Abstract: A capillary pulsed-discharge and a theta-pinch were used to record Kr spectra in the region of 330-4800 angstrom. A set of 168 transitions of these spectra were classified for the first time. We extended the analysis to twenty-five new energy levels belonging to 3s(2)3p(2)4d, 3s(2)3p(2)5d even configurations. We calculated weighted transition probabilities (gA) for all of the experimentally observed lines and lifetimes for new energy levels using a relativistic Hartree-Fock method, including core-polarization effects COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES Aberto

The $LMM$ Auger spectra of krypton are measured using the photon energies $h\ensuremath{\nu}=1709$ eV, 1792 eV, 1950 eV, and 13 keV. This approach allows separating the contributions from the various core holes ${L}_{1}, {L}_{2}$, and ${L}_{3}$. Previously unobserved transitions are presented. Complementary theoretical work is performed allowing the assignment of the spectral features. The ${L}_{2,3}Y\text{\ensuremath{-}}MMY$ ($Y={M}_{4,5},{N}_{1,2,3})$ Auger transitions of ${\mathrm{Kr}}^{2+}$ formed via Coster-Kronig Auger decay of the core holes ${L}_{1}$ and ${L}_{2}$ are also investigated. These spectra comprise about 4000 and 13 000 transitions, respectively, so that only general statements on the assignment, such as the configurations involved in the transitions, can be given.

A precision measurement of the rubidium ionic core polarizability has been realized at The University of Virginia. Development and implementation of a rubidium Rydberg state spectroscopy apparatus, an appropriate model for interpreting spectroscopic results, analysis, and conclusions are documented and presented herein. Due to experiment design, the spectroscopy measurements in this dissertation feature a greater precision and higher fidelity due to less pronounced systematic effects when compared to previous experiments. Furthermore, the implementation of a non-adiabatic core polarization correction leads to a core polarizability result that is more precise and commensurate with theory, potentially resolving a long-standing discrepancy between experiment and theory. These results may prove to be useful in future experiments and interpretation including, but not limited to: parity non-conservation, black-body radiation shifts in atomic clocks, and quantum computation.

The energy levels belonging to the configurations 3d/sup 7/4s/sup 2/ and 3d/sup 8/nl (nl = 4s, 5s, 4p, 5p, 4d, 5d, 4f, and 5g) have been calculated. The radial energy integrals were treated as parameters and adjusted to give a least-squares fit to the observed levels. Two- and three-body effective electrostatic interactions for equivalent electrons were included, as well as two-body effective interactions for inequivalent electrons. Strong configuration interaction between 3d/sup 7/4s/sup 2/ and 3d/sup 8/4d was taken into account. Values of the parameters are given for all the above configurations, and the calculated levels are given for all except 3d/sup 8/4s and 3d/sup 8/4p (for which essentially equivalent results have been published). Leading eigenvector percentages are given in appropriate coupling schemes.

The topic of atomic spectra is part of university and secondary school curricula around the world. Relatively little research, however, has been done on the learning and teaching of this subject, despite the fact that it forms a foundation for advanced study in quantum mechanics, astronomy, and astrophysics. A systematic investigation into student understanding of the formation and structure of atomic spectra was conducted among more than 1000 science majors in physics courses at the University of Zagreb, Croatia and the University of Washington, USA. The research had two primary goals: (i) to probe the extent to which university students are able to relate the wavelength of spectral lines to the transition of electrons between energy levels in an atom, and (ii) to probe the extent to which students recognize the conditions under which discrete line spectra are (and are not) formed. This paper focuses on the latter aspect, in particular, student understanding of the experimental setup that is commonly used to illustrate the formation of discrete line spectra. Students were asked about how changes to a setup consisting of a light source, a mask with a slit, a prism (or diffraction grating), and a screen affect the spectra observed. The findings suggest that relatively few students recognize that the type of light source is critical for the formation of line spectra. Instead students often attribute the formation of line spectra to the slit, the prism (or diffraction grating), or even to the distance between the prism and screen.

This is the second of two closely related articles (Paper I and Paper II) that together illustrate how research in physics education has helped guide the design of instruction that has proved effective in improving student understanding of atomic spectroscopy. Most of the more than 1000 students who participated in this four-year investigation were science majors enrolled in the introductory calculus-based physics course at the University of Washington (UW) in Seattle, WA, USA. The others included graduate and undergraduate teaching assistants at UW and physics majors in introductory and advanced physics courses at the University of Zagreb, Zagreb, Croatia. About half of the latter group were preservice high school physics teachers. Paper I describes how several conceptual and reasoning difficulties were identified among university students as they tried to relate a discrete line spectrum to the energy levels of atoms in a light source. This second article (Paper II) illustrates how findings from this research informed the development of a tutorial that led to improvement in student understanding of atomic emission spectra.

The near ultraviolet spectroscopy and photodissociation dynamics of two families of asymmetrically substituted thiophenols (2- and 3-YPhSH, with Y = F and Me) have been investigated experimentally (by H (Rydberg) atom photofragment translational spectroscopy) and by ab initio electronic structure calculations. Photoexcitation in all cases populates the 11ππ* and/or 11πσ* excited states and results in S–H bond fission. Analyses of the experimentally obtained total kinetic energy release (TKER) spectra yield the respective parent S–H bond strengths, estimates of ΔE(∼A−∼X), the energy splitting between the ground (∼X) and first excited (∼A) states of the resulting 2-(3-)YPhS radicals, and reveal a clear propensity for excitation of the C–S in-plane bending vibration in the radical products. The companion theory highlights roles for both geometric (e.g., steric effects and intramolecular H-bonding) and electronic (i.e., π (resonance) and σ (inductive)) effects in determining the respective parent minimum energy geometries, and the observed substituent and position-dependent trends in S–H bond strength and ΔE(∼A−∼X). 2-FPhSH shows some clear spectroscopic and photophysical differences. Intramolecular H-bonding ensures that most 2-FPhSH molecules exist as the syn rotamer, for which the electronic structure calculations return a substantial barrier to tunnelling from the photoexcited 11ππ* state to the 11πσ* continuum. The 11ππ* ← S0 excitation spectrum of syn-2-FPhSH thus exhibits resolved vibronic structure, enabling photolysis studies with a greater parent state selectivity. Structure apparent in the TKER spectrum of the H + 2-FPhS products formed when exciting at the 11ππ* ← S0 origin is interpreted by assuming unintended photoexcitation of an overlapping resonance associated with syn-2-FPhSH(v33 = 1) molecules. The present data offer tantalising hints that such out-of-plane motion influences non-adiabatic coupling in the vicinity of a conical intersection (between the 11πσ* and ground state potentials at extended S–H bond lengths) and thus the electronic branching in the eventual radical products.

The current paper reports first and definite experimental evidence for γ-, X-, or β radiation causing UV dominant optical radiation from (1) radiochemicals such as 131I; (2) XRF sources such as Rb XRF source present as salts; and (3) metal sources such as 57Co, and Cu XRF sources. Due to low quantum yield a need arose to develop two techniques with narrow band optical filters, and sheet polarizers that helped in the successful detection of optical radiation. The metal 57Co spectrum observed at room temperature hinted that it could be optical emission from excited 57Co atoms by a previously unknown phenomenon. In order to explain UV emission, it was predicted that some eV energies higher than that of UV, termed temporarily as Bharat radiation are generated within the excited atom, while γ-, X-, or β radiation passes through core-Coulomb field. In turn, the Bharat energy internally produced within the excited atom causes UV dominant high-energy spectrum by valence excitation. As excited atoms become free from surrounding unexcited atoms by valence excitation, room temperature atomic spectra of solid radioisotopes and XRF sources became a possibility. It implies existence of temporary atomic state of solids. The experimental evidence that γ-, X-, and β radiations causing UV dominant optical emission from within excited atoms of radioisotopes suggests the possibility for solar γ-, X-, and β radiations causing EUV by the atomic phenomenon described here.

The properties of monomials, homogeneous polynomials and harmonic polynomials in d-dimensional spaces are discussed. The properties are shown to lead to formulas for the canonical decomposition of homogeneous polynomials and formulas for harmonic projection. Many important properties of spherical harmonics, Gegenbauer polynomials and hyperspherical harmonics follow from these formulas. Harmonic projection also provides alternative ways of treating angular momentum and generalised angular momentum. Several powerful theorems for angular integration and hyperangular integration can be derived in this way. These purely mathematical considerations have important physical applications because hyperspherical harmonics are related to Coulomb Sturmians through the Fock projection, and because both Sturmians and generalised Sturmians have shown themselves to be extremely useful in the quantum theory of atoms and molecules.

Fullerenes have been a main focus of scientific research since their discovery due to the interesting possible applications in various fields like organic photovoltaics (OPVs). In particular, the derivative [6,6]-phenyl-C60-butyric acid methyl ester (PCBM) is currently one of the most popular choices due to its higher solubility in organic solvents compared to unsubstituted C60. One of the central issues in the field of OPVs is device stability, since modules undergo deterioration (losses in efficiency, open circuit voltage, and short circuit current) during operation. In the case of fullerenes, several possibilities have been proposed, including dimerization, oxidation, and impurity related deterioration. We have studied by means of density functional theory the possibility of oxygen adsorption on the C60 molecular moiety of PCBM. The aim is to provide guidelines for near edge X-ray absorption fine structure (NEXAFS) and X-ray photoelectron spectroscopy (XPS) measurements which can probe the presence of atomic or molecular oxygen on the fullerene cage. By analysing several configurations of PCBM with one or more adsorbed oxygen atoms, we show that a joint core level XPS and O1s NEXAFS investigation could be effectively used not only to confirm oxygen adsorption but also to pinpoint the bonding configuration and the nature of the adsorbate.

We propose a method for solving the vibrational Schrödinger equation with which one can compute spectra for molecules with more than ten atoms. It uses sum-of-product (SOP) basis functions stored in a canonical polyadic tensor format and generated by evaluating matrix-vector products. By doing a sequence of partial optimizations, in each of which the factors in a SOP basis function for a single coordinate are optimized, the rank of the basis functions is reduced as matrix-vector products are computed. This is better than using an alternating least squares method to reduce the rank, as is done in the reduced-rank block power method. Partial optimization is better because it speeds up the calculation by about an order of magnitude and allows one to significantly reduce the memory cost. We demonstrate the effectiveness of the new method by computing vibrational spectra of two molecules, ethylene oxide (𝖢 𝟤 𝖧 𝟦 𝖮) (C2H4O) and cyclopentadiene (𝖢 𝟧 𝖧 𝟨 ) (C5H6) , with 7 and 11 atoms, respectively.

International audience; We report anisotropic collision-induced Raman scattering intensities by the Kr–Xe atomic pair recorded in a gas mixture of Kr and Xe at room temperature. We compare them to quantum-mechanical calculations on the basis of modern incremental polarizability models of either ab initio post-Hartree–Fock or density functional theory methods.

The temporal behavior of gadolinium (Gd) laser-produced plasmas has been studied using a modified grazing incidence spectrometer which allows to capture the evolution of the plasma with spectral and temporal resolution of 0.1 nm and 1 ns, respectively. Experimental results indicate that the soft X-ray emission follows the temporal behavior of the laser pulse at high laser power density of Ф = 4.4×10 12 W/cm 2 in which the soft X-ray emission lasts for 7.5 ns (at FWHM) whereas at Ф = 5.4×10 11 W/cm 2 and Ф = 7.6×10 10 W/cm 2 the emission lasts for only 4 ns and 2.5 ns respectively , the s e are s horter than laser pulse duration due to lower electron temperatures achieved in the plasma generation. Lower Gd ion stages ranging from Gd 11+ – Gd 14+ are also found to contribute to the spectral emission over time. Received: 08 November 2013; Revised: 09 May 2014; Accepted: 09 May 2014

On etudie comment le comportement d’un electron dans des champs statiques electrique ou magnetique est modifie lorsque cet electron interagit egalement avec une onde electromagnetique haute frequence. Les nouvelles proprietes dynamiques de l’electron sont decrites par un hamiltonien effectif dont l’expression est etablie en utilisant une description quantique du champ electromagnetique et en tenant compte des corrections relativistes jusqu’a l’ordre 1 /c2. Outre une correction de masse bien connue, on trouve que les nouvelles proprietes dynamiques de l’electron peuvent etre comprises en termes de facteurs de forme electrique et magnetique qui ont une interpretation physique simple. Ces resultats generaux sont enfin appliques a 2 cas simples : perturbation des niveaux de Rydberg d’un atome et modification des frequences cyclotron et de precession de spin d’un electron dans un champ magnetique uniforme.

The method of Hartoog, Cowley, and Cowley (1973) is applied to the general question of element identification in HD 101065, which is often referred to as 'Przybylski's holmium star'. Three spectrograms are analyzed for wavelength coincidences, and a search is conducted for 187 atomic and ionic spectra of 92 elements. Most of the lanthanides, Ca II, and Y II are positively identified, but only weak evidence is found for the iron-peak elements. Some general remarks are made concerning the relative abundances (or absence) of Fe, Co, Y, Zr, Te, Tb, Lu, Yb, Nd, and U. No evidence is obtained for spectral variations or significant radial-velocity variations. It is concluded that iron-peak elements are present in this star, that their spectra are unusually weak with the possible exception of Co I, and that HD 101065 is apparently the only star of the magnetic chemically peculiar sequence with a lanthanide/iron-peak abundance ratio greater than unity.