September 21, 2015

UCLA physicists determine the three-dimensional positions of individual atoms for the first time

Mary Scott and Jianwei (John) Miao/UCLA
The scientists were able to plot the exact coordinates of nine layers of atoms with
a precision of 19 trillionths of a meter.

Finding will help scientists better understand the structural properties of materials

(September 21, 2015)  Atoms are the building blocks of all matter on Earth, and the patterns in which they are arranged dictate how strong, conductive or flexible a material will be. Now, scientists at UCLA have used a powerful microscope to image the three-dimensional positions of individual atoms to a precision of 19 trillionths of a meter, which is several times smaller than a hydrogen atom.

Their observations make it possible, for the first time, to infer the macroscopic properties of materials based on their structural arrangements of atoms, which will guide how scientists and engineers build aircraft components, for example. The research, led by Jianwei (John) Miao, a UCLA professor of physics and astronomy and a member of UCLA’s California NanoSystems Institute, is published Sept. 21 in the online edition of the journal Nature Materials.

For more than 100 years, researchers have inferred how atoms are arranged in three-dimensional space using a technique called X-ray crystallography, which involves measuring how light waves scatter off of a crystal. However, X-ray crystallography only yields information about the average positions of many billions of atoms in the crystal, and not about individual atoms’ precise coordinates.

“It’s like taking an average of people on Earth,” Miao said. “Most people have a head, two eyes, a nose and two ears. But an image of the average person will still look different from you and me.”

Because X-ray crystallography doesn’t reveal the structure of a material on a per-atom basis, the technique can’t identify tiny imperfections in materials such as the absence of a single atom. These imperfections, known as point defects, can weaken materials, which can be dangerous when the materials are components of machines like jet engines.

read entire press  release >>