Studies of the LIF radiation from beams of Sr+ and Br+ ions have been used to measure the lifetimes of the 4f and 5p levels of Sr II, and of the 4f, 6p and 7p levels of Ba II. The lifetimes obtained for the 5p levels of Sr II and the 6p levels of Ba II are in good agreement with previous LIF measurements. The fine structure of the 4f2F degrees term in Sr II has been resolved for the first time, the observed splitting being -1.30+or-0.06 cm-1. The energies of the two 4f levels have been measured as 60991.3 cm-1 (j=5/2) and 60990.0 cm-1 (j=7/2). The LIF decay curves recorded using a detector sensitive in the visible region for the 7p levels in Ba II showed very strong growing-in cascading, demonstrating that LIF decay curves are not necessarily single-exponential for high-lying levels. The lifetime results are compared with Coulomb approximation and RHF calculations where available, the latter including semi-empirical polarization corrections.
Laser excitation of a fast beam of Yb+ ions has been used to determine the lifetimes of the Yb II levels at 27062 cm-1 (8.10+or-0.13 ns), 33654 cm-1 (37.7+or-0.5 ns), 34575 cm-1 (28.6+or-0.4 ns) and 44941 cm-1 (20.3+or-0.3 ns). These results are compared with previous measurements and with the extensive calculation of Fawcett and Wilson (1991), with whom fair agreement is found for the level at 27062 cm-1 but marked disagreement is found for the other three levels.
Laser excitation of a fast beam of Yb+ ions has been used to make measurements of the radiative lifetimes of eight Yb II energy levels, four of which were excited via transitions from the ion-trap metastable level 4f ' 6s F;~z. Comparison is made with the lifetimes that may be derived from the semiempirical pseudorelativistic Hartree-Fock calculation by Fawcett and Wilson [At. Data Nucl. Data Tables 48, 241
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