Scheme 1.
Schematic for Anisotropic Singlet Fission in Hexacene Single Crystal
Anisotropic 1(T1T1) states are formed along the short b and long a axes directly from the hot S1S0 state. The rate for quantum decoherence along the short b axis is almost twice that along the long a axis. 1(T1aT1a) and 1(T1bT1b) represent correlated triplet pair states along the a and b axes, whereas T1a + T1a and T1b + T1b are triplet states along the a and b axes.