W. Ansbacher

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.

Beam-foil lifetime measurements for tellurium ions belonging to the Ag i and Cd i isoelectronic sequences

We have observed the spectrum produced by foil excitation of a beam of tellurium ions having an energy of 1 MeV. We have measured the lifetimes of the 5s5p1P1° and 3P1° levels, the 5s5d1D2 and 3D1,2,3 levels, and the 5p21D2 and 5s6s3S1 levels of Te v, and the 5p2P1/2,3/2°, 5d2D3/2,5/2, 6s2S1/2, and 6p2P1/2,3/2° levels of Te vi. The results are compared with a variety of calculations the agreement being quite good in most cases, particularly for the two resonance transitions at 895 A (Te v) and 951, 1071 A (Te vi), where our values were obtained using andc analyses. The variation of the f value with Z is discussed for the 5s2S–5p2P° transition along the Ag i isoelectronic sequence and for the 5s21S–5s5p1P° and 5s21S–5s5p3P° transitions along the Cd i isoelectronic sequence.

Energy-level and lifetime measurements for Sb IV and Sb V

A study of the beam-foil spectrum produced by a 1-MeV beam of antimony ions has yielded lifetimes for nine lowlying terms of Sb iv and six of Sb v. Decay-curve analysis incorporating the andc method to correct for cascade effects has given lifetimes for the upper state involved in the resonance transitions of both ions that are in reasonable agreement with most recent calculations. New energy-level assignments are given for the 5s5d1D2, 5s6d1D2, and 5s4f1F3 levels of Sb iv and for the 6d2D3/2,5/2 and 4f2F5/2,7/2 levels of Sb v.

Beam-foil spectroscopy for ions of lead and bismuth☆

Abstract The beam-foil technique is used to measure the lifetimes of levels in Pb III, Pb IV, Bi III and Bi IV. The problem of the energy loss incurred by heavy ions at the foil is discussed. Intensity decay curves including the region around the foil are analysed using VNET, a multiexponential fitting routine which includes the instrumental window function. These analyses are found to give results virtually identical with those obtained using normal curve-fitting of the data excluding the foil region in our case, where the window region only extends over one or two primary lifetimes. A comparison of the experimental and theoretical ƒ-values trends for the resonance transitions of the ions belonging to the gold and mercury isoelectronic sequences shows that the model potential used by Migdalek and Baylis in 1985 to allow for valence-core correlation gives good agreement with observation for the mercury sequence, whereas their similar calculation in 1979 for the gold sequence appears to give ƒ-values lower than those found by experiment for Tl III and Pb IV.

A modified Doppler-shift technique for fast ion velocity measurements

Abstract We describe a simple method for measuring the velocity of a fast ion beam to within ± 1%, and discuss the factors which determine the accuracy of the measurement.

New energy level identifications in Kr VI

Beam-foil delayed spectra from 89.0 to 101.0 nm are used to identify the intercombination lines connecting the 4s4p2 4P and 4s24p 2P levels in Kr VI. The existing analysis is extended to include the 4s25s 2S1/2, 4f 2F5/2, 2F7/2, 4p3 2D3/2, 2D5/2, 2P3/2, 4S3/2 and 4s4p2 4P1/2, 4P3/2, 4P5/2 levels. Lifetime measurements for the 4s4p2 4P1/2, 4P5/2, 4p3 2D3/2 and 2D5/2 levels are also discussed in support of these assignments.

Precision lifetime measurement of the z4D°52 level ofTi+ using laser excitation of a fast ion beam

Abstract An excimer laser has been used to populate the z 4 D° 5 2 level of Ti + ions in a fast beam. The observed decay of fluorescence intensity gives a lifetime of 4.01 ns with a one standard deviation uncertainty of ±0.06 ns.

Oscillator-strength measurements for the resonance transitions in Te v, Xe vii, and Xe viii

Oscillator strengths for the resonance transitions in Te v, Xe vii, and Xe viii are derived from andc analyses using beam-foil decay-curve data for these transitions and their major repopulating cascades. The results are in reasonable agreement with recent calculations in which allowance is made for interactions involving the electron core, these interactions resulting in a reduction of the oscillator strength of about 30% for all three transitions considered.

Pulsed laser measurements of the lifetimes of the 4p levels of Ca II

Abstract We report the first pulsed laser excitation measurements of the 4p level lifetimes for Ca II, viz. 6.96 ± 0.35 ns ( J = 1 2 ) and 6.71 ± 0.25 ns ( J = 3 2 ). We compare these values with several calculations and with the results obtained using a variety of other experimental methods, including some new beam-foil measurements using ANDC analysis.

Further energy-level and lifetime measurements for Kr vii

Beam-foil techniques are used to assign ten 4s5l and three 4s4f levels in Kr vii, based on 24 classified transitions. These assignments are supported by lifetime measurements and by studies of the variation in intensity of the classified transitions with beam energy. Lifetimes are reported for the 4s5p1P∘, 3P∘, and 4s5d3D levels. No J dependence was found for the lifetimes of the 4s5p P3J∘ levels, even though interaction with the 4p4d configuration was expected to produce such an effect. A puzzling inconsistency remains for the 4p2 1D2 level between the decay curve data and the assignment suggested by comparison with neighboring isoelectronic ions.