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

Abstract

Systematic studies of atomic lifetimes and oscillator strengths in the homologous atoms Ga, In, Tl and ${\mathrm{Ga}}^{+}$, ${\mathrm{In}}^{+}$, ${\mathrm{Tl}}^{+}$ 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.