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Highlights in Chemical Science

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Manipulating molecular motion

25 May 2006

Researchers in Germany say they have gained full control over the motion of polar ammonia molecules in a molecular beam.

Cynthia Heiner and colleagues at the Fritz Haber Institute used an instrument called a Stark decelerator to focus a beam of ammonia molecules and slow down the molecules to such an extent that they could be studied for seconds rather than milliseconds. The precisely controlled beams of molecules could be used for high-resolution spectroscopy, claim the researchers.


    Molecular beam apparatus


Attempts to manipulate ammonia molecules in the gas phase were inspired by 'both the impressive amount of control available for atoms and the simultaneous lack of a similar control for, arguably more interesting, molecules,' said Heiner.

Heiner claims the same techniques could be used to control larger, more intricate molecules, such as biomolecules, and their various conformational structures in the gas phase. 'We hope to see Stark decelerators become a wide spread tool for high resolution spectroscopy and collision studies', she said.

But there are many challenges still to overcome, said Heiner.  By increasing the densities of molecules, and simultaneously decreasing their temperature, experiments centred on cold collisions and molecular clocks could be carried out.  Stark deceleration of molecules provides the easiest way to access properties such as excited and ground state lifetimes, for the first time experimentally; 'now it is really time to play,' said Heiner.

Stephen Wilkes


CE Heiner, HL Bethlem and G Meijer, Phys. Chem. Chem. Phys., 2006 

DOI: 10.1039/b602260j