When going to ECISD+EHF, we notice several additional states interleaved between the local excitations. The S 1 -S 8 states of ECIS+EHF are found as S 1 -S 3 , S 5 -S 7 , and S 10 in ECISD+EHF. The leading ECSF of the S 4 state is 1 0 2T 1 ,4T 1 , corresponding to a triplet-triplet double-local excitation (TT-DLE). This is a so-called singletfission precursor state, which is very dark (exactly dark within SOA) and hence does not appear in the spectrum. Likewise, the S 8 and S 9 are also dominated by TT-DLE ECSFs.