Interactions between electronic states are omnipresent in nature as without them no chemical reaction can take place. But even when they do not lead to a reaction, their coupling can strongly influence the behaviour of a molecule after absorbing a photon. In the latest publication, we look into such an interaction between the two lowest excited singlet states of the neurotransmitter serotonin. Making use of the high sensitivity of rotationally resolved electronic spectroscopy to changes in electronic structure, we observe traces of couplings even if the two coupling states are energetically far apart.