Hi Please see the attached picture. It shows an atom, the filled black circle, which consists of a J=0 level (with m=0 sublevel) and J'=1 (with m' = +/- 1 sublevels). From the left is a nearly monochromatic laser impinging on the atom, which is linearly polarized along the same direction of the applied B-field. This situation will drive the Δm=0 transition, thus displaying a Lorentzian spectrum with FWHM given by the lifetime of the excited state (as a function of frequency). My question is, what will happen if the direction of the B-field is changed with 90 degrees, i.e. it is now parallel with k? This of course changes the quantization axis. My own suggestion is that I can always decompose the incoming linearly polarized light into two circularly polarized components of opposite helicity that drive the Δm = +/-1 transitions. But they will - contrary to the first situation - be Zeeman broadened. 1) Is my reasoning correct? 2) Say I want to model the spectrum numerically using a collection of atoms. Would it simply just be to take the spectrum for the Δm=-1 transition and add it to the spectrum for the Δm=+1 transition? Thanks for the help in advance. Best, Niles.