Even a normal camera can't capture the world in three dimensions, so imagine the challenge of getting a 3-D view of molecules. But Robert Magerle, a physicist at the University of Bayreuth in Germany, has done it, and his achievement might lead to products such as more comfortable shoes and more reliable computers.
Photo by Robert Magerle, Physical Review Letters 85, 2749, Copyright 2001 by the American Physical Society
Magerle worked with a scanning probe microscope, a device that taps a surface with a minute stylus and registers differences in hardness from spot to spot. With the microscope, he created an image of the surface of a synthetic rubber commonly used in shoe soles and pavement. He then blasted the rubber with charged molecules to strip off a layer just 0.0000003 inch thick, made another image, and repeated the process until the sample was completely worn away. Finally, he combined images of the many slices into a single, three-dimensional picture of the molecular strands in the rubber (above).
The result captures details about one ten-millionth of an inch wide and reveals the architecture of the strands in unprecedented detail. "The way the filaments are connected with each other determines if the material is stiff or soft. It's like a textile— how the fibers are connected with each other determines whether you can tear it easily or not," says Magerle. His method could allow engineers to fine-tune the molecular structure of plastics or to spot flaws in new semiconductor designs.
"Molecules in 3-D." "Nanotomography," Robert Magerle, Physical Review Letters, September 25, 2000, p. 2749; see prl.aps.org.