Measurement of the ratio of the squares of the reduced magnetic dipole matrix elements for the 876 nm and 648 nm transitions in atomic bismuth

Using Faraday spectroscopy, we have measured the ratio $\kappa$ of the squares of the reduced magnetic dipole matrix elements for the 876 nm ($^4$S$_{3/2}-^2$D$_{3/2}$) and 648 nm ($^4$S$_{3/2}-^2$D$_{5/2}$) transitions in the 6p$^3$ ground configuration of atomic bismuth. We find $\kappa = 8.75(25)$, in good agreement with theory