E. H. Pinnington

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.

Study of the beam-foil spectrum of Xe vi, and Xe vii, and Xe viii from 500 to 1550 Å

A survey has been made of the beam-foil spectrum of xenon between 500 and 1550 A at an energy of 1.6 MeV. Mean lives have been obtained from 18 lines, all but five of which have been classified as Xe vi, Xe vii, or Xe viii lines. Our proposed classifications for two lines would enable the 4f, 5g, and 6g terms in Xe viii to be connected to the rest of the system. Along the In i isoelectronic sequence, the oscillator strength of the 5s25p2Po−5s25d2D transition is compared with previous theory and experiment, and the wavelengths of the I v transitions in this sequence are proposed.

Beam-foil Studies of Phosphorus in the Vacuum Ultraviolet

We have measured lifetimes for 24 terms in P I-P V using the beam-foil technique in the vacuum UV region. The results have been compared with theoretical calculations and with other experimental values. Several significant discrepancies with earlier results have been found. We present the first experimental lifetimes for 9 terms. Most of our lifetimes can be converted directly into f-values, and we discuss these in relation to trends along isoelectronic sequences. Configuration interaction is found to be important for several transitions. We also suggest a revision of the recently-determined abundance of phosphorus in interstellar clouds, based upon our new f-value for the 1 308 ? multiplet in P II.

M1/E2/M2 decay rates in Fe VII, Fe IX, Fe X and Fe XIII measured using a heavy-ion storage ring

Lifetimes (the inverse of the total decay rates) of several 3p and 3d levels in Ca-, Ar-, Cl- and Si-like ions of Fe that decay only by electric-dipole-forbidden transitions have been measured optically using a heavy-ion storage ring, observing either near-UV or EUV light. In several cases, more than one decay contributes to a given decay curve, which complicates the analysis. The lifetime results, with a precision ranging from 0.8 to 10%, compare well with some theoretical predictions.

Precision lifetime measurement for the 3p levels of Mg II using frequency-doubled laser radiation to excite a fast ion beam

Abstract We report the first beam-laser measurement of the lifetimes of the 3p levels in Mg II. The measured lifetimes - 3.854±0.030 ns (j= 1 2 ) and 3.810±0.040 ns (j= 3 2 ) - agree closely with a recent calculation by Theodosiou and Curtis. We also report observations of both two-step and two-photon excitation of the 3d levels.

Lifetime Measurements in Ar ii–Ar viii

We have measured radiative decay times from the beam-foil spectra of Ar ii–Ar viii in the wavelength region 450–2450 A. The mean lifetimes for 20 excited levels are presented. We compare the results with theoretical calculations and other measurements and discuss the agreement with oscillator strengths in several isoelectronic sequences.

Mean-life Measurements for Levels in BI-BIV

We have studied beam-foil spectra of boron in the wavelength range 385 ? to 5 000 ?, and measured mean lives for 35 levels in B I-B IV. Where possible, we have deduced experimental oscillator strengths for the transitions studied, and we compare our results with other work both theoretical and experimental.

A Study of the Beam-Foil Spectrum of lodine from 400 to 1300 A

The beam-foil technique has been applied to study the iodine spectrum. New assignments are given for the I VI transitions 5s2 1S0-5s5p 1P10, 5s2 1S0-5s5p 3P10, 5s5p 3P00-5s5d 3D1, 5s5p 3P10-5s5d 3D2, 5s5p 3P20-5s5d 3D3 and 5s5p 1P10-5s7s 1S0, and tentatively for the I VII 4f-5g transition. Lifetimes have been measured for the 5s5p 1P10 and 3P10 levels of I VI and for the 5p 2P0 levels of I VII. MCHF calculations have been performed for two multiplets in I VI and for two multiplets in I VII. The experimental energies of the three lowest 1S terms are used to derive an I VI ionization potential of 72.9 eV.

Beam-foil mean-life measurements in krypton

Foil excitation of a beam of ionized krypton has yielded spectra in the wavelength range 434–1236 A for incident ion energies in the range 0.3–1.8 MeV. Radiative mean-life measurements have been performed using 32 transitions in Kr i-Kr viii. For several Kr vii and Kr viii transitions we have converted our mean-life results into absorption oscillator strengths for comparison with values suggested by Sorensen and co-workers by extrapolation along isoelectronic sequences.

Radiative Lifetime Measurements of Some Ar ii and Ar iii Levels by the Beam-Foil Technique

Radiative lifetimes have been measured from beam-foil spectra of 24 lines of Ar ii and 7 lines of Ar iii in the wavelength range 2400–5000 A. Agreement with the mean of other experimental results is to within 20%.