EXCITED-LEVEL LIFETIMES AND HYPERFINE-STRUCTURE MEASUREMENTS ON IONS USING COLLINEAR LASER ION-BEAM SPECTROSCOPY

The mean lifetimes tau of the Ca II 4p P-2(1/2) and 4p P-2(3/2) levels , and the Cl-35 II 4p' F-1(3) level, have been measured by a variant o f the collinear laser-ion-beam lifetime technique applied previously t o the Ar II 4p' F-2(7/2)o level [Jian Jin and D. A. Church, Phys. Rev. A 47, 132 (1993)]. The present results are tau(Ca II, 4p P-2(1/2)) = 7.098(0.020) ns, tau(Ca II, 4p P-2(3/2)) = 6.924(0.019) ns, and tau(Cl II, 4p' F-1(3)) = 11.17(0.06) ns. The experimental lifetimes of these , plus the Ar II 4p' F-2(7/2) level, are compared with available recen t many-electron calculations. Typically 1%-3% differences between meas urement and ab initio theory are found, while certain semiempirical ca lculations are in better agreement with experiment. Data for other pre cise lifetime measurements on alkali-metal systems are compared with r ecent ab initio and semiempirical calculations to provide perspective on the Ca II results. The hyperfine structure of the Cl-35 II 3d' 1G4- 4p' F-1(3) transition was also measured and analyzed in the course of the measurements, with the resulting hyperfine-structure constants: A( F-1(3)) = 301.9(0.5) MHz, B(F-1(3)) = -6.7(0.8) MHz, A(1G4) = 205.1(0. 5) MHz, and B(1G4) = -3.9(2.4) MHz.