Glimpsing Organic Molecules In Motion

Sneaking a peek at organic molecules as they move is tricky. The laser pulses typically used to initiate motion with most imaging techniques can thermally decompose the molecules or cause irreversible changes in the sample before researchers get any useful data. Scientists led by R. J. Dwayne Miller of the University of Hamburg, in Germany, and the University of Toronto have come up with a way around this problem. The team uses an ultrabright electron source that lets them determine a molecule’s structure without damaging the sample (Nature, DOI: 10.1038/nature12044). Miller and colleagues used femtosecond electron diffraction to track molecular movements in the organic salt ethylenedioxytetrathiafulvalene hexafluorophosphate as it undergoes a photo­induced insulator-to-metal phase transition. The technique, which uses laboratory-scale equipment rather than a synchrotron or an X-ray free-electron laser, monitors lattice structural changes on a timescale of just a few hundred femtoseconds. The researchers say this study establishes the potential of ultrabright femtosecond electron sources for studying labile chemical and biological systems.