Systematic Study of Atomic Lifetimes in Gallium, Indium, and Thallium Measured by the Beam-Foil Technique

Systematic studies of atomic lifetimes and oscillator strengths in the homologous atoms Ga, In, Tl and Ga⁺, In⁺, Tl⁺ have been performed by measuring mean lives of excited atomic states using the beam-foil technique. The lifetimes of the lowest S levels in the neutral atoms, 6.9 ±{}0.5, 7.5±{}0.7, and 7.7±{}0.5 nsec, respectively, for Ga, In, and Tl, are in agreement with recent reported values obtained by Hanle-effect and phase-shift techniques. Identical f values are found for homologous transitions in Al, Ga, In, and Tl, when configuration mixing can be excluded. The experimental results are compared with theoretical data based upon a single-configuration Coulomb approximation for neutral atoms and with a modified self-consistent-field approach for singly ionized atoms.