Direct Observation of Hyperfine Quenching of the (2)3p0 Level in Helium-Like Nickel

Journals published by the American Physical Society can be found at http://publish.aps.org/We report a clear demonstration of the effect of hyperfine quenching of a forbidden transition by direct comparison of the lifetimes of the 2 3P0 level in the heliumlike isotopes Ni-61(26+) and Ni-58(26+). We find the quenched lifetime of the 2 3P0 level in Ni-61(26+) to be 470(50) ps. From this we deduce the 2 3P0-2 3P1 energy splitting to be 2.33(15) eV. We also report a measurement of the lifetime of the 2 3P2 level in Ni-58(26+), which is found to be 70(3) ps

Electron-Transfer from H-2 and Ar to Stored Multiply Charged Argon Ions Produced by Synchrotron Radiation

Journals published by the American Physical Society can be found at http://publish.aps.org/The rate coefficients for electron transfer from Ar and H-2 to Ar(q+) ions (3 less-than-or-equal-to q less-than-or-equal-to 6) have been measured using an ion-storage technique in a Penning ion trap. The ions were produced in the trap by K-shell photoionization of Ar atoms, using broadband synchrotron x-ray radiation. K-electron removal resulted in vacancy cascading, yielding a distribution of argon-ion charge states peaked near Ar4+. The stored ion gas had an initial temperature near 480 K. The basic data determining the rate coefficients k(Ar(q+)) are the storage time constants of each charge state in the trap, in the presence of a measured pressure of target gas. The results of the measurements (in units of 10(-9) cm3 s-1) are k(Ar3+, H-2) = 4.3(0.7), k(Ar3+, Ar) = 1.6(0.2), k(Ar4+, H-2) = 5.2(0.6), k(Ar4+, Ar) = 2.5(0.3), k(Ar5+, H-2) = 5.9(0.7), k(Ar5+, Ar) = 2.9(0.3), k(Ar6+, H-2) = 8.5(l.2), and k(Ar6+, Ar) = 2.5(0.3)