) are proportional to ∑ nm𝑄 P 3 n𝑯 -𝑻𝐃𝟐 n𝐷 P pn P 2 . 37, 51 Fig. . shows schematic representations of the sublevel populations in the quartet states by using the elements of nm𝑄 P 3 n𝑯 -𝑻𝐃𝟐 n𝐷 P pn in Table . As reported previously, the spin polarization can be generated due to the sublevel selectivity in the D-Q interaction at the thermal activations. More importantly, such sublevel selective population is anisotropic due to the anisotropy of the ZFS (𝑯 -(),-. ). Thus, in the absence of quick isotropic diffusion rotations, the ZFS interactions contribute not only to the fine structure, but also to the spin polarization anisotropy in Fig. by the microwave resonance, denoting that the anisotropic activation motion can be characterized from the polarized EPR data in fluid solutions.