Given the high symmetry of the molecular structure of TAB due to its trimeric structure, it is expected that there are three equivalent sites where the triplet-exciton is distributed, and we assumed that the triplet-exciton hops between these sites (Orientations A, B and C) at the hopping rate constant "𝑘 LMC " (Figure ). Since the three anthracene moieties of TAB are arranged in a 3D orthogonal relationship, the hopping causes three orientations of the triplet-exciton to rotate by 90° about two of the axes (x, y, z) within a coordinate frame in the molecule. Such a change in the orientation of the triplet-exciton leads to motional narrowing of the EPR spectra as the pseudo-rotation, which is effectively equivalent to molecular rotation. Details are described in the Supporting Informational on the EPR spectrum analysis using the coupled stochastic-Liouville equations (SLE) considering the A⇄B, B⇄C, and C⇄A interconversions by 𝑘 LMC in the rotating frame with Figure -S12 and Table , S4. Validities of the fitting parameters are examined as detailed in Table and Figure .