Fig. 1.

(A) Schematic view of the electron-then-hole DAE pathways (upper route via $|d,a*\rangle$), hole-then-electron DAE pathways (lower route via $|a,d*\rangle$), and mixed electron/hole bridge-exciton BE pathways (routes through the center block of the bridge-exciton states $\left\{|b_n,b_m^{*}\rangle \right\}$). The DAE pathways (upper and lower routes, dotted lines) avoid the BE manifold $\left\{|b_n,b_m^{*}\rangle \right\}.$ The BE pathways (dashed lines to and from the center block) avoid $|d,a*\rangle$ and $|a,d*\rangle$. (B) Schematic diagrams of hole- and electron-occupied orbitals in the DAE state $|d,a*\rangle$ and in a BE state $|b_1,b_2^{*}\rangle .$ For example, NLMO orbitals $|b_1\rangle$ and $|b_2^{*}\rangle$ could correspond to the first σ bond and the second $\sigma *$ antibond of the alkane bridge in Fig. 2A.