Figure 9.

Orientation of TDM vectors for (a) duplex dimer, (b) transverse dimer, and (c) type 2 tetramer derived by modeling the optical properties of the materials via an approach based on KRM theory. The TDM vector orientations were derived in Section S15. Green double-headed arrows correspond to TDM vectors, which are taken to lie along the long axis of the Cy5 dye. Dashed lines indicate the critical approach distance derived by modeling; see the main text for further details. The critical approach distance for the duplex dimer (i.e., J-aggregate) was taken to be the end-to-end distance, while the critical approach distance for the transverse dimer and type 2 tetramer (i.e., H-aggregates) was taken to be the center-to-center distance.