CT Scan for Molecules; April 2005; Scientific American Magazine; by Graham P. Collins; 2 Page(s)

In the quantum world, objects are described by wave functions. Electrons around a molecule, for example, exist in wavelike orbitals, smeared-out shapes that determine properties such as the electrons' energy and the propensity for the molecule to undergo various chemical reactions. But orbitals are slippery critters that, because of Heisenberg's uncertainty principle, defy routine efforts to image them completely and accurately. Now, however, researchers at Canada's National Research Council in Ottawa have produced a three-dimensional scan of the outermost electron orbital around a nitrogen molecule. The "shutter speed" of the imaging method is fast enough that scans might one day be taken of molecules caught in the middle of a chemical reaction.

The group, led by Paul B. Corkum and David M. Villeneuve, uses a laser pulse lasting just 30 femtoseconds (3 X 10^-14 second). During the course of the laser pulse, the electric field of the light wave oscillates about a dozen times. Each oscillation drives the outermost electron of the nitrogen molecule away from the molecule and back again.