Besides, Table demonstrates that the theoretical calculations produce much larger ISC and RISC rate coefficients for S 1 -T 2 crossings than those for S 1 -T 1 crossings. This is reasonable because the former possess a much smaller energy gap and larger SOCME, shown in Tables and. Considering the NAC vector between T 1 -T 2 in Table , we deduce that the population transfer between singlet and triplet states of 7-PhQAD additionally takes place via S 1 -T 2 -T 1 channel except the direct S 1 -T 1 transition.