Forbidden Lines of Bismuth BiI

Abstract

A group of forbidden lines of bismuth BiI, namely γ8755, 6476, 5640, 4615, 4597, and 3014, all belonging to transitions between levels of the configuration $6p^3$ (Fig. 1) was investigated with a spectrograph of high resolving power. The hyperfine structures observed are collected in Table I and the photographs obtained are reproduced in Fig. 2. Predicted patterns with components corresponding only to the change of the quantum number $F$ by 0 or ±1 and intensities calculated on basis of usual formulas for electric dipole radiation are in best agreement with the observed ones (Fig. 3). The absence of components corresponding to $\Delta F=\pm 2$ shows the predominantly magnetic dipole character of the radiation. All observed separations of components and wave-lengths of the forbidden lines found are in very good agreement with the values predicted on basis of the highly accurate level scheme of the bismuth atom previously determined by the author.