K. E. Donnelly

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.

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.

Radiative Lifetime Measurements in Al II-VII

We have used the beam-foil technique to study spectra of aluminium in the wavelength range 300 A to 2000 A, and measured radiative mean lives for 22 levels in Al II-Al VII. Where possible, our results are compared with theory and other experimental work.

Beam-foil spectroscopy of bromine from 450 to 1000 Å

Beam-foil excitation of the bromine spectrum has been applied to the measurement of radiative lifetimes for eight terms in Br v to Br vii, using HBr+ ions of energy 0.5–1.6 MeV. The multiplet f values derived from these results are found to be reasonably consistent with other measurements for the analogous transitions in homologous atoms, except for the 4s4p2 2D term in Br v, where configuration interaction is known to be important. Agreement within a factor of two is found with f values forecast by calculations based upon the Coulomb approximation. The behavior of the f values of the 4s2 1S–4s4p1P0 and 4s4p3P0–4s4d3D transitions along the Zn i isoelectronic sequence is considered in detail, and again the experimental results are consistent with each other but differ from f values calculated by several techniques by a factor of about two. Many previously unclassified lines have been observed, and tentative assignments are suggested for five of these. Decay curves have also been recorded for nine spectral features in the region 550–650 A, which suggest that the 1P0, 1D0, 3P0, and 3D0 terms of the 4p4d configuration in Br iv all have lifetimes in the range 0.08–0.14 ns.

Mean-life measurements for some terms in C II, C III, and C IV

Radiative mean lives have been measured for six terms in C ii, seven terms in C iii, and two terms in in C iv using the beam-foil technique.