Ultrafast separation of electrical charge within a molecule during a photochemical reaction causes up to ten thousand neighboring molecules to reorient themselves in molecular pirouettes. Now researchers have for the first time directly observed such light-induced alignment of molecules in an organic crystal. The scientists from the Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy in Berlin and the Ludwig Maximilians University in Munich report about it in the latest issue of the journal Physical Review Letters (Volume 98, page 248301).
For their study, they used extremely short pulses of light to create a separation of positive and negative electric charges in individual molecules, to which the molecules of the environment then react with a change in their spatial orientation. For the first time, researchers captured this fundamental process by diffracting femtosecond x-ray pulses with high precision and in real time.