Filming the Invisible in 4D: New Microscopy Makes Movies of Nanoscale Objects in Action
- Four-dimensional electron microscopy produces “movies” of nanoscale processes occurring over time intervals as short as femtoseconds (10–15 second).
- The technique builds up each frame of the movie from thousands of individual shots taken at precisely defined times.
- It has applications in a wide range of fields, including materials science, nanotechnology and medicine.
The human eye is limited in its vision. We cannot see objects much thinner than a human hair (a fraction of a millimeter) or resolve motions quicker than a blink (a tenth of a second). Advances in optics and microscopy over the past millennium have, of course, let us peer far beyond the limits of the naked eye, to view exquisite images such as a micrograph of a virus or a stroboscopic photograph of a bullet at the millisecond it punched through a lightbulb. But if we were shown a movie depicting atoms jiggling around, until recently we could be reasonably sure we were looking at a cartoon, an artist’s impression or a simulation of some sort.
In the past 10 years my research group at the California Institute of Technology has developed a new form of imaging, unveiling motions that occur at the size scale of atoms and over time intervals as short as a femtosecond (a million billionth of a second). Because the technique enables imaging in both space and time and is based on the venerable electron microscope, I dubbed it four-dimensional (4-D) electron microscopy. We have used it to visualize phenomena such as the vibration of cantilevers a few billionths of a meter wide, the motion of sheets of carbon atoms in graphite vibrating like a drum after being “struck” by a laser pulse, and the transformation of matter from one state to another. We have also imaged individual proteins and cells.
Originally published by the Scientific American. Read the original story here