x,y ). Both models lead to virtually the same effect. Fig. shows the result of a simulation with a coupling via the x-component of the spin-orbit coupling, assuming a value of γ x = 0.8 cm -1 for a normalized displacement. This results (for molecules oriented along the z-axis) in an intersection of the spin-transitions and the phonon transition at a field strength of ca. 6 T and leads to a difference spectrum (averaged over all orientations) that is in good agreement with the experimental one.