Inside Back Cover: Ultrafast Excitonic Transitions in Enantiopure and Racemic Squaraine Thin Films

Enantiopure ProSQ-C16 thin films exhibit an unusually large excitonic circular dichroism signal. Using steady-state and ultrafast transient absorption spectroscopy, Bernhardt et al. reveal that the optical response and its circular dichroism originate from a single type of predominantly J-like aggregated ProSQ-C16 molecules. A rapid transition to a dark intermediate state via intermolecular charge transfer and exciton-vibration coupling is suggested to be responsible for the suppression of the fluorescence, highlighting the importance of non-Frenkel exciton dynamics (e698).