Arbitrarily Normalized Decay Curve Research Articles

Determination of polarizabilities and lifetimes for the Mg, Zn, Cd and Hg isoelectronic sequences

The dipole polarizability and adiabatic correlations of atomic ions are related to the energy levels and oscillator strengths of the levels through bracketing inequalities. For systems with a ground state ns2 1S0, the total oscillator strength is dominated by the unbranched intrashell ns2 1S0–nsnp 1Po1 transition, and the remaining oscillator strength can be narrowly bracketed using the f-sum rule. Thus measurements of the lifetime of the lowest resonance transition can be used to specify the polarizabilities and, alternatively, measurements of the polarizabilities can be used to deduce lifetimes. Moreover, isoelectronic regularities in line strengths can be used to obtain a comprehensive database from a small number of precision lifetime determinations. These methods are applied homologously to produce values for polarizabilities and lifetimes for the Mg, Zn, Cd and Hg isoelectronic sequences. To confirm the reliability of these methods, fast ion beam lifetime measurements in P IV were performed using the arbitrarily normalized decay curve (ANDC) method, and a test of the f-sum was made for Ba II, for which precision measurements of both the polarizability and lifetimes exist.

Lifetime Measurements in Snii

Lifetime measurements are reported for levels arising from the 5s25d and 5s24f configurations in Sn II. Measured decay curves were jointly analyzed using the Arbitrarily Normalized Decay Curve (ANDC) method to remove the effects of cascade repopulation from the determination of the lifetimes of the 5s25d2D3/2 level. The branching ratio of the decay of this level to the ground term fine-structure levels 2P1/2 and 2P3/2 was carefully measured, and we have obtained an accurate value for the absorption oscillator strength of the resonance transition to this level at 1400.52 Å. The results are discussed in the context of interpreting vacuum ultraviolet absorption spectra observed with the Goddard High Resolution Spectrograph on board the Hubble Space Telescope.

Beam - foil study of the lifetimes of levels in Na-like Ca X, Mg-like Ca IX and Si-like Ca VII

Levels of Ca ions with one, two or four electrons in the n = 3 shell have been studied for their decay properties and lifetimes. For the levels of Ca X and the level of Ca IX, arbitrarily normalized decay curve (ANDC) and cascade model analyses yield results with precisions of 10% and less and with low systematic uncertainties. The measured lifetime of the Ca IX level confirms the need to include relativistic effects in the calculation. The lifetime results are compared to other, experimental and theoretical, data available for the isoelectronic sequences.

Energy level lifetimes obtained from ANDC analyses for the 3 d4F0J ( J = 3/2, 5/2, 7/2, 9/2) energy levels in NIII

An in-depth cascade-corrected energy level lifetime analysis of the 3 d 4 F 0 3/2, 5/2, 7/2, 9/2 energy levels in N III was undertaken by studying the primary 3 d 4 F 0 J -3 p 4 D J transitions, as well as investigating the influence of all major cascading levels, namely the higher lying 4 p 4 D J , 4 f 4 D J , 4 f 4 F J and 4 f 4 G J energy levels. A few of these levels were indeed found to have a marked influence on the lifetimes of the 3 d 4 F 0 J energy levels. These influences were studied using a multi-exponential curve-fitting technique, as well as the now well-proved ANDC (Arbitrarily Normalized Decay Curve) technique. The Beam-foil method using these techniques is expected to provide a reliable and consistent experimental check on the various theoretical calculations. The present paper describes beam-foil measurements of the lifetimes of a number of 2 s 1 2 p 1 ( 3 P 0)3 d, 4 p and 4 f levels in N III.

Beam-foil study of the 3 p5S02 and 3 p5P01,2,3 energy level lifetimes in O III

We have studied the light emitted by oxygen ions in the wavelength region 200–500 nm, accelerated by the Van de Graaff accelerator of the National Accelerator Centre at Faure. Lifetime measurements by the beam-foil method are discussed in this report and a detailed study was undertaken to investigate the influence of cascading on the lifetimes of the observed 3 p 5 S 0 2 and 3 p 5 P 0 1,2,3 energy levels in O III by utilizing the arbitrarily normalized decay curve (ANDC) method. Since these results may be considered as representing the real lifetime of these energy levels, it served as a test for the lifetimes obtained by various theoretical approximations and may provide information regarding the effects of electron correlation in these systems. The present values were also used for comparison with the experimental values obtained by other workers.

Radiative lifetimes of some quartet levels in P III

Using beam energies of 0.40, 0.75 and 1.00 MeV and the beam-foil technique, we observed the phosphorus spectrum between 200.0 and 500.0 nm. We measured the lifetimes of the 5 s 4 P 3/2, 4 d 4 P 5/2, 3/2, 4 d 4 D 7/2, 5/2, 4 p 4 S 3/2 and 4 p 4 P 5/2, 3/2 levels in P III. Specific attention was paid to the problem of cascade correction by applying the arbitrarily normalized decay curve (ANDC) technique. The first three levels were used as cascading levels to produce lifetimes for the 4 p 4 S 3/2 (τ = 2.57 ns), 4 p 4 P 5/2 (τ = 2.74 ns) and 4 p 4 P 3/2 (τ = 2.71 ns) levels.

Beam-foil lifetime measurements in Pb III and Pb IV

Beam-foil intensity decay curves for transitions in the wavelength range from 900 to 2200 Å are used to derive the lifetimes of the 6s6p1P1 and 3P1 6s6d1D2, 6s7s1S0, and 6p21D2 levels of Pb III, and the 6p2P1/2 and 2P3/2, 6d2D3/2 and 2D5/2, 7s2S1/2, and 5d96s22D3/2 levels of Pb IV, arbitrarily normalized decay curve (ANDC) analyses being used for the 6s6p and 6p levels. In the case of the two 6s6p levels studied in Pb III, good agreement is found with a recent calculation in which a polarization model accounts for valence–core correlation. However, the agreement between the lifetimes observed for the 6p levels in Pb IV and a similar, earlier calculation is only fair.

Cascade Corrected Beam-Foil Lifetimes of the 3p 4D1/2,3/2,5/2,7/20 Energy Levels in O II

The 3p 4D1/2,3/2,5/2,7/20 energy levels in O II were investigated by means of beam-foil excitation and the resultant lifetimes were corrected for cascade effects using the arbitrarily normalized decay curve (ANDC) technique. The results are compared with theoretical calculations, as well as results obtained by other workers.

Radiative lifetime measurements of the 3 p3S1 energy level in O III

The beam-foil technique has been used to measure the lifetime of the 3 p 3 S 1 energy level in O III. The possibility of cascading from higher lying states is discussed and the most prominent cascades that repopulate this level are explicitly included in the analysis through the application of the ANDC (Arbitrarily Normalized Decay Curve) technique. The results are compared with theoretical calculations and also measurements performed by other workers.

Beam-foil measurements of the 3 p3P and 3 p3D energy levels in O III

The beam-foil excitation technique has been applied to study the spectra of oxygen in the 200–500 nm wavelength region. Decays of the 3 p 3 P and 3 p 3 D energy levels in O III have been identified unambiguously and the ANDC (arbitrarily normalized decay curve) technique was utilized to investigate the influence of cascades on the lifetimes of these levels. These lifetimes are compared with theoretical calculations and data from other workers.

Beam-foil mean lifetimes in Kr II obtained from ANDC analysis

Detailed measurements on the 5p 4 S 3 2/0 and 5p∼' 2 D 5 2/0 levels in Kr II are reported. Cascade effects were taken into account with the aid of the arbitrarily normalized decay curve (ANDC) technique. Experimental values are compared to values obtained by other investigators as well as to theoretical values.

Radiative liferimes in O II obtained from beam-foil experiments

Detailed measurements on the3p′2F0 and3d′2G levels in O II are reported. The most prominent cascades that repopulate these levels are explicitly included in the analysis through the application of the ANDC (Arbitrarily Normalized Decay Curve) method. The results are compared with theoretical calculations and also measurements performed by other workers.

Beam-foil mean lifetimes in Kr III obtained from arbitrarily normalized decay curve (ANDC) analyses

Detailed measurements on the 5 p 5 P level in Kr III are reported. The most prominent cascades that repopulate the 4 s 24 p ( 4 S 0) 5 p 5 P level are explicitly included in the analysis through the application of the arbitrarily normalized decay curve (ANDC) method. The results are compared with theoretical calculations and also measurements performed by other workers.

Beam-Foil Lifetime Measurements Using ANDC Analysis for the Resonance Doublet in Ar VIII, Kr VIII and Xe VIII

Some practical methods are suggested for applying the Arbitrarily Normalized Decay Curve (ANDC) method for cascade-correction in beam-foil lifetime measurements. These methods are used to analyze decay curves recorded for the ns2S-np2P0 resonance doublet in Ar VIII, Kr VIII and Xe VIII by including the np2P0-nd2D cascade transitions in the analysis. The f-values derived from the np lifetimes for the ns-sp multiplet are in good agreement with recent theoretical estimates for Ar VIII and Kr VIII and agree with theory for Xe VIII within the combined experimental and theoretical uncertainties.

Mean-life measurements for some fluorine transitions in the quartz region

The beam-foil technique has been applied to the measurement of the mean lives of seven terms in F III and three terms in F IV, giving rise to transitions in the wavelength range 2150 to 3200 Å. The results are compared with other experimental and theoretical values. Forecasts are made for f-values of some F IV transitions below 500 Å in the 2s2p3–2s22p3p array. Examples of the application of the arbitrarily normalized decay curve (ANDC) method for including the effects of cascade repopulation in the data analysis are discussed.