Terahertz pulses manipulate molecular networks

A newly developed “tractor beam” can be used to manipulate networks of molecules, essentially softening crystals without heating them up.

Until now, softening methods always have raised the temperature of crystals, changing their structure and properties, often with undesirable effects. The new technique uses terahertz pulses and could be broadly applicable to pharmaceutical and other chemical industries.

A team at the Koichiro Tanaka lab at Kyoto University’s Institute for Integrated Cell-Material Sciences used intense terahertz pulses to increase the amplitude of movement between amino acid molecules in crystalline form, which, in essence, softened the crystals. The article, written by Mukesh Jewariya, Masaya Nagai and Koichiro Tanaka, was published online Nov. 11, 2010, in Physical Review Letters.

“What we have demonstrated is that it is possible to use intense terahertz pulses to climb 20 ladder steps on the anharmonic intermolecular potential in the microcrystals,” said Nagai, an assistant professor at the university’s physics department. “This opens the door to the possibility of manipulating large molecules, thereby increasing understanding of the properties of molecular complexes such as proteins.”

The team expects the technique to lead to eventual advances in chemical synthesis as well as in the refining of organic molecular crystals for pharmaceutical purposes.