Figure 5: Quadratic Zeeman-induced anti-crossing.
From: Si:P as a laboratory analogue for hydrogen on high magnetic field white dwarf stars
A detail around 44 meV and 3.5 T of the Si:P absorption (Fig. 2) is shown in white. Superimposed are the theoretical circularly polarized transitions (that is, those which have direct correspondence with free hydrogen): red open/solid symbols, Δm=−1; blue solid symbols, Δm=+1 (and diameter proportional to the magnitude of the dipole matrix element). The excellent agreement between the experiment and theory is evident. The red open symbols highlight the 4f– (starts at 43.7 meV at 0 T) and 5p– (starts at 44.2 meV). The transition 1s to 4f– is only weakly allowed by the anisotropy (it is strictly forbidden at B=0 in hydrogen), while the 5p– is strongly allowed. The transitions anti-cross at about 3.5 T and so that the 4f– line gains p– character, while the 5p– gains f– character. The dashed lines are guides to the eye, indicative of the positions of the two levels without their mutual interaction.
