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Robert Duane Cowan

Bio: Robert Duane Cowan is an academic researcher. The author has contributed to research in topics: Atomic spectroscopy. The author has an hindex of 1, co-authored 1 publications receiving 3672 citations.

Papers
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Book
25 Sep 1981
TL;DR: In this article, the Slater-Condon theory of atomic structure and spectra is combined with a coherent set of closed-form equations suitable both for computer calculations on cases of arbitrary complexity and for hand calculations for very simple cases.
Abstract: Both the interpretation of atomic spectra and the application of atomic spectroscopy to current problems in astrophysics, laser physics, and thermonuclear plasmas require a thorough knowledge of the Slater-Condon theory of atomic structure and spectra. This book gathers together aspects of the theory that are widely scattered in the literature and augments them to produce a coherent set of closed-form equations suitable both for computer calculations on cases of arbitrary complexity and for hand calculations for very simple cases.

3,826 citations


Cited by
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01 Jan 2013
TL;DR: In this paper, the ab initio quasirelativistic Hartree-Fock method developed specifically for the calculation of spectral parameters of heavy atoms and highly charged ions is used to derive transition data for a multicharged tungsten ion.
Abstract: a b s t r a c t The ab initio quasirelativistic Hartree–Fock method developed specifically for the calculation of spectral parameters of heavy atoms and highly charged ions is used to derive transition data for a multicharged tungsten ion. The configuration interaction method is applied to include electron correlation effects. The relativistic effects are taken into account in the Breit–Pauli approximation for quasirelativistic Hartree–Fock radial orbitals. The energy level spectra, radiative lifetimes and Lande gfactors are calculated for the 4p 6 4d 2 , 4p 6 4d4f, and 4p 5 4d 3 configurations of the ion W 36+ . The transition wavelengths, spontaneous transition probabilities, oscillator strengths, and line strengths for the electric dipole, electric quadrupole, electric octupole, and magnetic dipole transitions among the levels of these configurations are tabulated.

1,704 citations

Journal ArticleDOI
TL;DR: The updated version of the “Vienna Atomic Line Data Base” (VALD) is described which represents a considerable improvement over the first installation from 1994 and the future roadmap of VALD developments is discussed, including the incorporation of molecular transitions and integration with external data bases.
Abstract: We describe the updated version of the “Vienna Atomic Line Data Base” (VALD, Piskunov et al. 1995) which represents a considerable improvement over the first installation from 1994. The original line lists have been complemented with critically evaluated data obtained from experimental measurements and theoretical calculations which are necessary for computing state-of-the-art line opacities in stellar atmospheres, as well as for synthesizing spectra for high precision analyses. In this paper, we present new and improved data sets for neutral species and ions of Si, P, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Ru, Xe, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu, Re, Pt, Au, Hg, and Pb. For some species data are available in VALD for the first time. We explain our choice of quality rankings by reviewing the literature for the new data and by comparison with source lists included into VALD. For some cases, we produced new line data by weighted averaging of data from different sources with individual error estimates in order to increase the reliability of VALD line lists. Software modifications allow remote users of VALD to specify individual extraction parameters as an alternative to the default settings of the VALD team and to have direct control over the quality ranking of line data. A World–Wide–Web interface is described which provides easy access to all new features. To simplify proper crediting of all authors of atomic data, VALD now includes a compilation of all publications used in each type of reply. Finally, we briefly discuss the future roadmap of VALD developments, including the incorporation of molecular transitions and integration with external data bases.

1,641 citations

Reference BookDOI
10 Mar 2008
TL;DR: In this article, a detailed overview of core level spectroscopies can be found, including XPS and XAS spectra, as well as a comparison of the two spectra with single electron excitation models.
Abstract: INTRODUCTION FUNDAMENTAL ASPECTS OF CORE LEVEL SPECTROSCOPIES Core holes Overview of core level spectroscopies Interaction of x-rays with matter Optical transition operators and x-ray absorption spectrum The interaction of electrons with matter X-ray sources Electron sources MANY-BODY CHARGE-TRANSFER EFFECTS IN XPS AND XAS Introduction Many-body charge-transfer effects in XPS General expressions of many-body effects General effects in XPS spectra Typical examples of XPS spectra Many-body charge-transfer effects in XAS Comparison of XPS and XAS CHARGE TRANSFER MULTIPLET THEORY Atomic multiplet theory Ligand field multiplet theory The charge transfer multiplet theory X-RAY PHOTOEMISSION SPECTROSCOPY Introduction Experimental aspects XPS of TM compounds XPS of RE compounds Resonant photoemission spectroscopy Hard XPS Resonant inverse photoemission spectroscopy Nonlocal screening effect in XPS Auger photoemission coincidence spectroscopy Spin polarization and magnetic dichroism in XPS X-RAY ABSORPTION SPECTROSCOPY Basics of XAS Experimental aspects The L2, 3 edges of 3d TM systems Other x-ray absorption spectra of the 3d TM systems X-ray absorption spectra of the 4d and 5d TM systems X-ray absorption spectra of the 4f RE and 5f actinide systems X-RAY MAGNETIC CIRCULAR DICHROISM Introduction XMCD effects in the L2, 3 edges of TM ions and compounds Sum rules XMCD effects in the K edges of transition metals XMCD effects in the M edges of rare earths XMCD effects in the L edges of rare earth systems Applications of XMCD RESONANT X-RAY EMISSION SPECTROSCOPY Introduction Rare earth compounds High Tc Cuprates and related materials Nickel and Cobalt compounds Iron and Manganese compounds Early transition metal compounds Electron spin states detected by RXES and NXES MCD in RXES of ferromagnetic systems APPENDICES Precise derivation of XPS formula Derivation of Eq. (88) in Chapter 3 Fundamental tensor theory Derivation of the orbital moment sum rule Theoretical test of the spin sum rule Calculations of XAS spectra with single electron excitation models REFERENCES INDEX

937 citations

Journal ArticleDOI
TL;DR: In this article, the authors review recent developments in Kα and Kβ spectroscopy and show how the chemical sensitivity of the fluorescence lines can be exploited for selective X-ray absorption studies.

775 citations

Journal ArticleDOI
TL;DR: In this paper, a review of high-resolution X-ray emission and Xray absorption spectroscopy is presented, where the focus is on the 3D transition-metal systems.
Abstract: In this review, high-resolution X-ray emission and X-ray absorption spectroscopy will be discussed. The focus is on the 3d transition-metal systems. To understand high-resolution X-ray emission and reso-nant X-ray emission, it is first necessary to spend some time discussing the X-ray absorption process. Section II discusses 1s X-ray absorption, i.e., the K edges, and section III deals with 2p X-ray absorption, the L edges. X-ray emission is discussed in, respectively, the L edges. X-ray emission is discussed in, respec-tively, and section V on 2p3s and 2p3d X-ray emission. Section VI focuses on magnetic dichroism effects, and in section VII selective X-ray absorption experiments are discussed. To limit the scope of this review paper, many related topics (for example, EELS, XPS, and resonant photoemission, phonon-oriented inelastic X-ray scat-tering, and X-ray microscopy) will not be discussed. In addition, many aspects of X-ray absorption, such as reflection experiments, diffraction absorption fine structure, and related experiments, will remain untouched. EXAFS will be discussed very briefly, and its X-ray emission analogue EXEFS 69,71 will not be discussed.

700 citations