Determination of atomic properties in the oxygen isoelectronic sequence

We report mean-life results for 16 terms in S III–S VI, obtained from vacuum ultraviolet transitions in sulfur excited by beam–foil interaction. Ten of the mean lives have been measured for the first time. Many of the mean lives reported here are in the neighborhood of 0.1 ns, beyond the time resolution capability of a previous experiment, as indicated by comparison of results for five of the remaining six terms. For those transitions that are unbranched. we have computed the absorption oscillator strength and we discuss the values in the context of isoelectronic-sequence trends. In an appendix, we discuss the determination of short mean lives and describe the apparatus we have developed to measure them, and its limitations.

Download Full-text

An expansion method for calculating atomic properties. IX. The dipole polarizabilities of the lithium sequence*

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1966.0177 ◽

1966 ◽

Vol 293 (1434) ◽

pp. 365-377 ◽

Cited By ~ 17

Keyword(s):

Nuclear Charge ◽

Expansion Method ◽

Zero Order ◽

Isoelectronic Sequence ◽

Hartree Fock ◽

Atomic Properties ◽

Dipole Polarizabilities

A theory is developed for expanding the dipole polarizabilities and shielding factors of an atom or ion in inverse powers of the nuclear charge Z in cases where the field links degenerate zero order configurations. Results for all members of the lithium isoelectronic sequence are presented both within the Hartree-Fock approximation and in a more accurate formulation, and are found to be in agreement with earlier work.

Download Full-text

The total electronic band structure energy for 29 elements

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1966.0213 ◽

1966 ◽

Vol 294 (1438) ◽

pp. 376-392 ◽

Cited By ~ 61

Keyword(s):

Band Structure ◽

Electronic Band Structure ◽

Model Potential ◽

Electronic Band ◽

Atomic Properties ◽

Phonon Spectra ◽

Metal Properties ◽

Band Structure Energy ◽

Electron Band Structure

The total electronic band structure energy is calculated for 29 elements by the method of the screened model potential of Heine & Abarenkov (1964). The division of the total energy of a metal into free electron, band structure, and electrostatic parts follows the method initiated by Harrison (1963) for the calculation of atomic properties. By drawing an analogy with the procedure introduced by Cochran (1963) for the experimental determination of the electronic contribution to phonon spectra of metals, we arrive at a more convenient expression for the total band structure energy in a form applicable to the determination of atomic properties, phonon spectra, general interatomic forces, and possibly liquid metal properties. Numerical results are compared with those derived from experiment and from the o. p. w. pseudopotential method.

Download Full-text

IAU Colloquium No. 8: Experimental Techniques for the Determination of Fundamental Spectroscopic Data

International Astronomical Union Colloquium ◽

10.1017/s0252921100028189 ◽

1971 ◽

Vol 8 ◽

pp. 48-60

Author(s):

Bruce W. Shore

Keyword(s):

Spectral Line ◽

Energy Levels ◽

Oscillator Strengths ◽

Atomic Data ◽

Fast Time ◽

Line Profiles ◽

Atomic Properties ◽

University Of Edinburgh ◽

Experimental Spectroscopy

The last ten years have brought significant changes to the venerable disciplines of astronomy and spectroscopy. Traditionally astronomers sought wavelength catalogues of identified spectra lines. Under this impetus spectroscopists laboured to provide very accurate wavelength measurements and estimates of emission line intensity. Physicists and astronomers alike are now recognizing interest not only in such properties of isolated atoms as energy levels (or spectral-line wavelengths) and oscillator strengths, but also those atomic properties which depend upon the surroundings of a radiating atom: spectral-line profiles, excitation rates, and level populations. In turn, new uses of lasers and interferometers, fast time resolution, and simple but significantly different absorption and emission samples are altering experimental spectroscopy almost beyond recognition. The present colloquium, chaired by A.H.Cook (University of Edinburgh) and held at Imperial College, London, on September 1-4 1970, aimed to identify the means by which astronomers can now obtain fundamental atomic data.

Download Full-text

An expansion method for calculating atomic properties X. 1 s 2 1 S -1 snp 1 P transitions of the helium sequence

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1967.0206 ◽

1967 ◽

Vol 301 (1466) ◽

pp. 253-260 ◽

Cited By ~ 54

Keyword(s):

Cross Sections ◽

Nuclear Charge ◽

Expansion Method ◽

Probable Error ◽

Oscillator Strengths ◽

Matrix Elements ◽

Isoelectronic Sequence ◽

First Order ◽

Hartree Fock ◽

Atomic Properties

The electric dipole matrix elements connecting the 1 s 2 1 S and 1 snp 1 P states of the helium isoelectronic sequence are calculated exactly to first order in inverse powers of the nuclear charge Z and the differences from the Hartree-Fock approximation are shown to correspond to virtual transitions of the 1 s electrons. Comparison of the oscillator strengths predicted by a screening approximation with more accurate values reveals a regular variation in the error contained in the screening approximation, the correction of which allows the prediction of oscillator strengths and probabilities of 1 s 2 1 S – 1 snp 1 P transitions for all values of n and all values of Z within a probable error of 2% (table 5). Values of the photoionization cross-sections at the spectral heads are also presented.

Download Full-text