X-rays reported to trigger crystal formationPublished on January 27th, 2010 | By: firstname.lastname@example.org
A team from Northwestern University reports in the new issue of Science about the role that X-rays can play in crystal formation. The researchers say they accidentally discovered that X-rays can trigger the formation of a new type of crystal that is composed of charged cylindrical filaments. These crystals are ordered like a bundle of pencils experiencing repulsive forces.
They hope their work will expand the use of X-rays from not just an analytical tool but also a method to control the structure of materials.
In a NU press release, Samuel Stupp, one of the paper’s authors, describes what the group thinks is going on with the X-rays. “The filaments are charged so one would expect them to repel each other, not to organize into a crystal. Even though they are repelling each other, we believe the hundreds of thousands of filaments in the bundles are trapped within a network and form a crystal to become more stable,” says Stupp, who is a professor of chemistry, materials science and engineering and medicine.
The discovery happened when members of Stupp’s research team, working on a separate organic project, zapped a solution of peptide nanofibers with synchrotron X-ray radiation. Unexpectedly, the solution turned opaque. “There was a dramatic change in the way filaments scattered the radiation,” says coauthor Honggang Cui. “The X-rays turned a disordered structure into something ordered – a crystal.”
The group theorizes that the X-rays increase the charge of the material and causes a hexagonal stacking of filaments. They say that because of repulsive forces, the filaments are positioned far apart from each other, with as much as 320 angstroms separating the filaments.
Back to Previous Page