Science 323, 1464–1468 (2009)

Molecules in gases and liquids are always moving thanks to their thermal energy. This means that measuring many details of their dynamics, which would require accessing the interaction of the molecule with nearby molecules and light, is impossible. However, by using a short laser pulse, a molecule can be 'frozen' for a few picoseconds (10−12 seconds), a time sufficient to examine, using ultrafast spectroscopy, the characteristics of its molecular dynamics.

Albert Stolow of the Steacie Institute for Molecular Sciences in Ottawa, Canada, and his colleagues demonstrate their method with the carbon disulphide molecule, observing its dynamics in a photochemical reaction.