Fig. 6. Polarized reflectivity of mixed-stack complexes.

a Spectra of mixed-stack complexes obtained in the electric field of light parallel to the π-stacking direction. Bars indicate the top of the peaks. The spectrum of the relatively thin single-crystal 2O–F₄ exhibits stripe-pattern signals in the low-energy region due to interference from the backside (the raw data is shown in Supplementary Fig. 34a), and thus this part of the spectrum was deleted for clarity. b Temperature-dependent reflectivity of 2S–F₄ in the electric field of light parallel (//) and perpendicular (⊥) to the π-stacking directions for the low-energy region.