Excitation of Zn+* levels in Penning and charge transfer reactions of He*(23S1) and He+with zinc

Abstract

Thermal, Penning and charge transfer reactions of He*(23S1) metastable atoms and He+ ions with zinc were studied in a flowing afterglow apparatus. The absolute values of the rate constants for excitation of the individual Zn+* levels have been measured. In Penning ionisation only 3.2 and 2.0% of the Zn+ ions are produced in the states which correspond to upper levels of the 747.9 and 589.4 nm laser lines respectively, while 90% of the ions are directly formed in the ground state. In charge transfer reactions, the fraction of the Zn+ ions excited in the four high lying 6p2P, 5d2D, 4f2F and 6s2S states is about half of the product Zn+ ions, 45% being produced in 5d2D levels. The remaining half are equally distributed between levels of the 3d94s(3D)4p configuration and other levels down to a few eV below the energy of the He+ ion. The authors have also measured the total Penning ionisation and charge transfer rate constants: k(PI)=(7.1+or-1.4)*10-10 cm3 s-1 and k(CT)=(7.4+or-1.4)*10-10 cm3 s-1 respectively.