Say NO to Straddling Molecules

“Imagine you are standing, John Wayne style, on the backs of two runaway horses pulling a stagecoach. You try to bring the horses to a stop but instead the harnesses break, the horses separate, and an unlucky passenger gets thrown from the stage.”

That’s how the latest chemistry news release from Sandia National Laboratories. Poetic in its own way, I suppose, but couldn’t they have got the scientist in question Carl Hayden to put on a ten-gallon hat for the photo shoot at least?

The news release goes on to explain how he and colleagues at SNL and the National Research Council in Ottawa, Canada, and elsewhere, straddled a molecule by, in effect, standing on pair after pair of joined nitric oxide molecules (NO dimers) and watching as each pair split after being excited by an ultrashort laser pulse.

The researchers not only measured the direction of each separating NO molecule but also the direction and energy of an electron spat out as each molecular break up occurred. The electron reveals the quantum energy levels of the dimer as it separates.

Then, computer back calculations from the final speeds and angles provided the team with a way to reconstruct the event and so “see” the exact path the electron and each dimer fragment had taken, exactly as though they had ridden on the dimers as they split.

The detailed experimental results, reported in Science, allow the team to test the computational methods used for combustion and atmospheric modelling involving NO.