Fig. 4: Relative electronic and vibronic contributions to optical spectra and sensitivity of the absorption spectrum to oblique angle.

a, b Electronic and vibronic contributions to the steady-state absorption and CD spectra of the SR dimer structure. c Schematic showing the oblique angle between two molecules in a dimer that was varied to produce the absorption spectra in d. The TDMs of the molecules are represented with arrows and are assumed to be oriented along the long axis of the molecule. The oblique angle is varied by rotating the TDM around the point indicated by the black circle. The dashed line corresponds to a relative orientation between molecules where α = 0°. d Simulated absorption spectra as a function of oblique angle, α. Dipoles are assumed to be coplanar with a fixed distance of nearest approach, modeled using parameters determined from the experimental data of the SR monomer and dimer solutions. e Plot of the ideality factor, η, as a function of α. When η = 1, the electronic bands are of equal intensity; when η = 1, the electronic bands exhibit their maximum intensity difference. The dashed black line represents the α output from the KRM modeling for the SR dimer.