Zeeman Effect of the Forbidden Lines of Pb I I. Pure Quadrupole and Magnetic Dipole Lines

Abstract

A very intense source of the forbidden lines, consisting of a high frequency discharge through helium containing a small amount of lead vapor, is used to photograph the Zeeman patterns in fields up to 4000 gauss. Reproductions are given of the transverse effect for the main hyperfine component, due to the even isotopes, in a magnetic dipole line, $\ensuremath{\lambda}4618$, and in two quadrupole lines, $\ensuremath{\lambda}\ensuremath{\lambda}4659$ and 5313. The reversal of polarization in $\ensuremath{\lambda}4618$ is clearly shown. The splittings of the weaker hyperfine components emitted by ${\mathrm{Pb}}^{207}$ are also observed for $\ensuremath{\lambda}\ensuremath{\lambda}5313$ and 4618, including, in the latter case, fields strong enough to show the Back-Goudsmit effect. Splittings and intensities are in satisfactory agreement with theory throughout. These are the first observations on the Zeeman effect of the hyperfine structure of forbidden lines, and they establish the applicability of the electric dipole intensity formulas (with interchange of polarization) to magnetic dipole lines and of the Rubinowicz quadrupole formulas (with suitable substitutions of quantum numbers) to quadrupole lines.