Measurements of experimental transition probabilities of 3p54p → 3p54s arrays in neutral argon.

We present new results of transition rates for twenty two electric dipole transitions of neutral krypton associated with the 4p55p→4p55 s configurations-based levels covering the wavelength region from 500 to 1000 nm using a krypton filled hollow cathode discharge lamp coupled with a set of four miniature spectrometers. The branching fractions of various dipole allowed transitions were extracted using the observed line intensity ratios, whereas, the absolute values of the transition probabilities were deduced from the measured branching fractions in combination with the known lifetimes of the upper levels. The experimental data are in good agreement with that calculated in the intermediate angular momentum coupling scheme. In addition, line strengths for all the transitions have been extracted using the measured transition probabilities. The J-file sum rule was also tested for each level attached to the 4p55p→4p55 s configurations based on the recently measured and calculated normalized multiplet strengths.

view Abstract Citations (57) References (21) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Branching Fractions and Oscillator Strengths for Fe II Transitions from the 3d 6( 5D)4p Subconfiguration Bergeson, S. D. ; Mullman, K. L. ; Wickliffe, W. E. ; Lawler, J. E. ; Litzen, U. ; Johansson, S. Abstract New experimental branching fractions and transition probabilities are reported for 56 transitions in Fe II. The branching fractions are measured with a Fourier transform spectrometer and also with a high-resolution grating spectrometer on an optically thin hollow cathode discharge. Highly accurate experimental radiative lifetimes from the recent literature provide the normalization required to convert our branching fractions into absolute transition probabilities. Results are compared with experimental and theoretical values in the literature. Our new transition probabilities will establish the absolute scale for relative absorption oscillator strengths of vacuum ultraviolet lines measured using a new high-sensitivity absorption experiment at the University of Wisconsin. Publication: The Astrophysical Journal Pub Date: June 1996 DOI: 10.1086/177391 Bibcode: 1996ApJ...464.1044B Keywords: ATOMIC DATA; ISM: ABUNDANCES; ULTRAVIOLET: GENERAL full text sources ADS |

In this work experimental transition probabilities, line strengths, and atomic oscillator strengths of 30 spectral lines corresponding to the 2p53p → 2p53s transitions array of neon have been deduced using a neon-filled hollow cathode lamp in conjunction with two spectrographs covering the wavelength region from 500 to 1000 nm. The experimental absolute transition probabilities have been determined using the relative intensity method and lifetimes of the excited states. The transition probabilities have been converted to the line strengths data and used for testing the J-file sum rule. Relative line strengths of all the lines have been computed to determine the oscillator strength values. The measured transition probabilities, oscillator strengths, and relative line strengths agree well with the previously reported data.

Absolute radiative transition probabilities are reported for 559 strong lines of neutral cerium covering the wavelength range 340–880 nm. These transition probabilities are obtained by scaling published relative line intensities (Meggers et al 1975 Tables of Spectral Line Intensities (National Bureau of Standards Monograph 145)) with a smaller set of published absolute transition probabilities (Bisson et al 1991 J. Opt. Soc. Am. B 8 1545). All 559 new values are for lines for which transition probabilities have not previously been available. The estimated relative random uncertainty of the new data is ±35% for nearly all lines.

Absolute atomic transition probabilities for emission lines from 70 levels in Sc i and Sc ii are reported. The transition probabilities are from emission branching ratios measured using the 1.0-m Fourier-transform spectrometer at the National Solar Observatory. Radiative lifetimes, measured using time-resolved laser-induced fluorescence, provide the normalization for converting the branching ratios to absolute transition probabilities. These results are compared with other experimental and theoretical transition probabilities.

Summary from only given. High efficiency electrical light sources used in lighting applications are based on electrical discharges in plasmas. The systematic search for improved lighting plasmas increasingly relies on plasma discharge modeling with computers and requires better and more comprehensive knowledge of basic atomic data such as radiative transition probabilities and collision cross sections. NIST has ongoing research programs aimed at the study of thermal equilibrium plasmas such as high pressure electric arcs and non-equilibrium plasmas in radio-frequency discharges and high current hollow cathode lamps. In emission experiments we have measured branching fractions and determined absolute transition probabilities for spectral lines in Ne I, Ne II, F I, O I and O II. In case of the Ne measurements the line radiation emitted by a high current hollow cathode lamp was analyzed with a 2 m monochromator. In addition, the spectra of Ne I and Ne II were measured with a UV Fourier transform spectrometer at very high spectral resolution. The line intensities were subsequently calibrated to absolute radiances. Where complete sets of transitions from an upper level could be observed, recent lifetime data for these levels were used to determine absolute transition probabilities. The accuracy of our branching fraction data is 5% for the stronger lines.

New emission branching fraction (BF) measurements for 183 lines of the second spectrum of chromium (Cr II) and new radiative lifetime measurements from laser-induced fluorescence for 8 levels of Cr+ are reported. The goals of this study are to improve transition probability measurements in Cr II and reconcile solar and stellar Cr abundance values based on Cr I and Cr II lines. Eighteen spectra from three Fourier Transform Spectrometers supplemented with ultraviolet spectra from a high-resolution echelle spectrometer are used in the BF measurements. Radiative lifetimes from this study and earlier publications are used to convert the BFs into absolute transition probabilities. These new laboratory data are applied to determine the Cr abundance log ε in the Sun and metal-poor star HD 84937. The mean result in the Sun is 〈logε (Cr II)〉 = 5.624±0.009 compared to 〈logε(Cr I)〉 = 5.644 ± 0.006 on a scale with the hydrogen abundance log ε(H) = 12 and with the uncertainty representing only line-to-line scatter. A Saha (ionization balance) test on the photosphere of HD 84937 is also performed, yielding 〈logε(Cr II)〉 = 3.417 ± 0.006 and 〈log ε(Cr I, lower level excitation potential E. P. >30 eV)〉 = 3.3743±30.011 for this dwarf star. We find a correlation of Cr with the iron-peak element Ti, suggesting an associated nucleosynthetic production. Four iron-peak elements (Cr along with Ti, V, and Sc) appear to have a similar (or correlated) production history-other iron-peak elements appear not to be associated with Cr.

Absolute transition probabilities of some Kr I lines

E1 transition probabilities between the nilsson states [formula omitted

New absolute atomic transition probability measurements are reported for 12 transitions in Cr II and two transitions in Zn II. These transition probabilities are determined by combining branching ratios measured by classical techniques and radiative lifetimes measured by time-resolved laser-induced fluorescence. The measurements are compared with branching fractions, radiative lifetimes, and transition probabilities in the literature. The 206 nm resonance multiplets in Cr II and Zn II are included in this work. These multiplets are very useful in determining the distribution of the elements in the gas versus grain phases in the interstellar medium.

Experimental transition probabilities of infrared lines belonging to the 4 p-3 d transition array of Ar(I)

Relative line strengths have been computed for the transition arrays of 3p54s–3p54p and 3p54s–3p55p in Ar i. Intermediate-coupling theory has been used, starting from LS coupling, and using the experimental energy levels as data for determining the parameters of the theory by least-squares adjustment of the calculated energies. The results have been placed on an absolute scale using the Coulomb approximation. The Lande g factors computed agree well with the observed values. The calculated transition probabilities are in fairly satisfactory agreement with various experimental determinations, and this agreement is better than that obtained using either LS- or jl-coupling calculations. The results for the 4s–4p array appear to be more accurate than those for the 4s–5p array.

Absolute transition probabilities in NbI and Hfl and a solution to the problem of missing infrared branches

Transition probabilities and branching ratios of Co II lines

We report the simultaneous measurements of radiative lifetimes, branching fractions, and absolute transition probabilities in atomic samarium using laser-induced fluorescence. The radiative lifetimes of seven odd-parity energy levels and six step-wise-excited even parity energy levels of atomic samarium have been measured. The lifetime values of odd-parity energy levels agree well with those reported in the literature, and the values of even-parity energy levels are new. Excited-level-to-ground-level branching fractions and absolute transition probabilities for twenty-one transitions in atomic samarium are measured using single-color laser-induced fluorescence, and the results are compared against the values reported in the literature. We also report branching fractions and absolute transition probabilities for fifty-one excited-level-to-excited-level transitions in atomic samarium using two-color laser-induced fluorescence. The existing ambiguity in assigning the total angular momentum values for the six stepwise-excited even-parity energy levels is removed by assigning each of these excited levels a unique J value by identifying known odd-parity lower levels to which a stepwise-excited even-parity level decays via fluorescence decay channels.