Oscillator Strengths Of Resonance Lines Research Articles

Accurate Calculation of Mgii3s–npOscillator Strengths

A careful and accurate semiempirical calculation of transition matrix elements yielded the oscillator strengths of resonance lines for the lowest np configurations in Mg II. Through an extension of previous work, particular attention was given to the determination of branching ratios for the fine-structure levels in the upper states. The new f-values provide strong theoretical support to the recent astronomical determinations by Fitzpatrick (1997) and could settle the question of the Mg abundance in the interstellar medium. The branching ratio f(3s-4p3/2)/f(3s-4p1/2) = 1.78, a value that deviates from the assumed ratio of 2 used in earlier work.

Systematic calculations of correlation in complex ions

Systematic calculations of atomic properties, using the Multiconfiguration and Configuration Interaction techniques, are discussed. Different quality criteria for atomic structure calculations are pointed out, and examples are given to illustrate these points. Among the properties discussed are oscillator strengths for resonance lines, magnetic dipole hyperfine structure constants, lifetimes of metastable states, transition probabilities of intercombination lines, and level structure of rare earth elements. New results are presented for the 3s23p2 3PJ – 3s3p3 5S2 transitions in silicon-like systems.

Measurements of broadening of argon lines and oscillator strengths of resonance lines

In the present paper, we report on line broadening of Ar I associated with collisions between neutral argon atoms (3 p 5 4 p - 3 p 5 4 s transitions) in a weakly ionized plasma jet (neutral atom temperature T 0 ⋍ 4000°K, electron temperature T e ⋍ 6000°K, electron density N e < 10 15 cm -3, ionization rate α < 10 -4, and pressure range from 1 to 3 kgf/cm 2). The neutral atom temperature, which is an important parameter in comparing theoretical and experimental results, is deduced from the surface temperature of a tungsten wire when heated by the Joule effect. This measurement, which has been performed both in a vacuum and in a plasma, gives good results without requiring the use of a heat-transfer coefficient between the wire and the plasma. A satisfactory description of van der Waals' broadened lines is obtained by means of a Lennard-Jones potential. Measurements of line widths for resonance transitions yield good values for the strengths of argon resonance lines.

Oscillator strengths of resonance lines in Br(VI), (VII) and Kr(VII), (VIII)

Oscillator strengths of the resonance lines in Br(VI) and Kr(VII) (Zn(I) iso-electronic sequence) and in Br(VII) and Kr(VIII) (Cu(I) iso-electronic sequence) have been obtained from measurements using the beam-foil technique in the vacuum u.v. Results are compared with other measurements in the same sequences and with recently calculated values. There is serious disagreement between theory and measured results.

Hook-Method Measurements of gf-VALUES for Ultraviolet fe i and fe II Lines on a Shock Tube

view Abstract Citations (24) References (16) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Hook-Method Measurements of gf-values for Ultraviolet Fe I and Fe II Lines on a Shock Tube Huber, Martin C. E. Abstract Transition probabilities for 14 lines of Fe ii and 12 lines of Fe I in the wavelength region 25602737 A were measured by use of a shock tube and the hook method. Absolute oscillator strengths for resonance lines of Fei reported by Banfield and Huber were used to determine the number density of neutral iron in the shock-heated gas. With the assumption of thermal equilibrium, the density of singly ionized iron atoms in this gas was then computed from the measured temperature and pressure with the aid of the Saha equation. Our results on the 12 strongest of the 13 lines belonging to the first ultraviolet multiplet of Fe ii indicate that the multiplet f-value is larger by a factor of 2 than that derived from lifetime measurements by Assousa and Smith. Subject headings: spectra, laboratory - spectra, ultraviolet - transition probabilities Publication: The Astrophysical Journal Pub Date: May 1974 DOI: 10.1086/152868 Bibcode: 1974ApJ...190..237H full text sources ADS |

Oscillator strengths of the resonance lines of some rare gases

The oscillator strengths of several resonance lines of He, Ne, Ar and Kr in the wavelength range between 522 Å and 1165 Å have been determined by measuring the self-absorption of the radiation as a function of the gas pressure at low pressures. The self-absorption of the radiation of the 1 1S-2 1P line of He is used as a reference. An absorbing pathlength of 2.8 cm and pressures in the range from 5 x 10 −6 to 10 −3 torr were used. The obtained values of the oscillator strengths of the resonance lines are: 2 helium 3 1P-1 1S ( 537 Å) f = 0.076 ± 0.004, helium 4 1P-1 1S ( 522 Å) f = 0.029 ± 0.002, neon 1P 1- 1S 0 ( 736 Å) f = 0.134 ± 0.010, argon 1P 1- 1S 0 (1048 Å) f = 0.22 ± 0.02, krypton 1P 1- 1S 0 (1165 Å) f = 0.142 ± 0.015.

Oscillator strengths for resonance lines of some silicon and sulfur ions

Oscillator strengths are calculated for resonance lines of some silicon and sulfur ions, which are present in the solar spectrum from about 160 Å to 380 Å. Spin-spin and spin-other orbit interactions are included. A comparison is made with Garstang's results for Six; agreement is good.

Oscillator Strengths for Resonance Lines of Ions in the Neon Isoelectronic Sequence

view Abstract Citations (32) References (9) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Oscillator Strengths for Resonance Lines of Ions in the Neon Isoelectronic Sequence Kastner, S. O. ; Omidvar, K. ; Underwood, J. H. Abstract Oscillator strengths are calculated for some extreme ultraviolet resonance lines of ions in the neon isoelectronic sequence, on the basis of single configurations in intermediate coupling. Making plausible assumptions concerning the conditions of excitation in the corona and in spark sources, we find fairly good agreement with observation in the case of the important coronal Fe xvii lines, but the results of the calculations disagree with the few observations of earlier ions in the sequence. If the comparison is meaningful, configuration interaction may be responsible. Publication: The Astrophysical Journal Pub Date: April 1967 DOI: 10.1086/149144 Bibcode: 1967ApJ...148..269K full text sources ADS |