A. G. Trigueiros

Transitions in Multiply Excited FVI and FVII

The transitions 1s2s2p2 5P-1s2p3 5S0 in F VI and 1s2s2p 4P0-1s2p2 4P in F VII have been investigated using the method of beam-foil spectroscopy. The fine-structure separations have been determined for the 1s2s2p2 5P term in F VI and for both 4P terms in F VII. The results are compared with recent theoretical calculations of fine structure, based on relativistic wavefunctions, and with previous experimental data. Lifetime measurements are reported for the 1s2p2 4P5/2 level and the 1s2p3 5S20 level.

Revised and extended analysis of the low configurations in Kr iii

The spectrum of doubly ionized krypton (Kr iii) was studied in the 430–8200-A range. Approximately 140 new Kr iii lines were classified as transitions between levels of the 4s24p4, 4s4p5, 4s24p34d, 5s, and 5p configurations, and approximately 150 were reclassified. The energy-level system reported for these configurations by Moore [ Natl. Bur. Stand. Circ.467 ( 1957)] was revised and extended to include three new levels of the 4s24p34d configuration and one level of the 4s24p35p configuration.

Lifetimes of the 2s2p1P Level in Be-Like NIV and OV Obtained from Beam-Foil Experiments and Extensive Cascade Analyses

Lifetime measurements using the beam-foil method are reported for the 2s2p 1P level in Be-like N IV and O V. The results, 0.425 ± 0.015 ns in N IV and 0.338 ± 0.015 ns in O V, are in excellent agreement with the majority of recent theoretical results. The existing systematic discrepancy between theory and experiments in this sequence is thereby removed for these two ions. It is shown that this agreement is possible only when the most prominent cascades that repopulate the 2s2p 1P level, are explicitly included in the analysis through the application of the ANDC method. Lifetimes of these cascading levels are also reported and are found to be in good agreement with previous experimental and theoretical results.

Accurate Experimental Lifetimes of Excited Levels in Sodiumlike Sulfur, S VI

The lifetimes of the terms 3p 2P, 3d 2D, 4s 2S, 4p 2P, 4d 2D, 4f 2F, 5g 2G, 6g 2G, 6h 2H, 7h 2H, 7i 2I and 8k 2K in sodiumlike sulfur, S VI, have been determined using the beam-foil excitation technique. Most of the decay curves were analyzed by means of the ANDC method which corrects for cascading in a very detailed way. Accurate results were thereby obtained which show that an excellent agreement exists between experimental and theoretical values. Some previously noted disagreements between the results of beam-foil experiments and theoretical investigations are explained as being due to less accurate analyses of the experimental data.

Revised and Extended Analysis of Five Times Ionized Argon (Ar VI)

The spectrum of five times ionized argon, (Ar VI), has been observed in the 280-2100 A wavelength range. Eighty-seven lines have been identified as transitions between levels of the 3s23p, 3s3p2, 3s23d, 3p3, 3s3p3d, 3s24s, 3s24d and 3s3p4s configurations. For 33 of the lines the classification is new. Forty-one energy level values belonging to these configurations were analyzed and we propose 9 new energy level values for levels corresponding to odd parity configurations. The configurations are interpreted by fitting the theoretical energy expressions to the observed energy levels using leastsquares techniques. The parameter values are compared with results from Hartree-Fock calculations.

Lifetimes of the 3p 2P1/2, 2P3/2 and 3d 2D3/2, 2D5/2 Levels in Cl VII

The beam-foil excitation technique has been applied to determine lifetimes of the 3p 2P1/2, 2P3/2 and 3d 2D3/2, 2D5/2 levels in Na-like Cl VII. Using the ANDC method accurate values have been obtained which confirm recent theoretical values and explain some previously noted differences between theoretical and experimental oscillator strengths for transitions in multiply ionized Na-like ions.

The 3d-4f Transition in S VII Observed in a Laser-Produced Plasma

The energy levels of the 2p54f configuration in neon-like sulphur, S VII, have been derived from spectral lines in the region 330-375 A. The lines, which were identified as belonging to the 3d-4f transition, were emitted from a laser-produced plasma. The structure in the 4f configuration has been studied through a parametric fit of Slater integrals.

Dissociation of CN+ into atomic excited states after acceleration in a tandem accelerator

Abstract A CN + beam produced by stripping CN - in the terminal of a Pelletron Tandem accelerator was dissociated in a thin carbon foil. Optical observations of ultraviolet transitions of C III–C IV and IV - N V showed intensity variations as a function of foil thickness. The results indicate an enhancement of population due to the neighboring partner projectile for some but not all excited states.