Candid camera at the nanoscale

UC IRVINE (US)—Can single molecules in motion be caught on camera? A research team thinks so, and is working to make the first real-time videos of single molecules in action, a feat that has proved elusive because size and time scales are so small.

Success would greatly accelerate the pace of nanoscience—which is behind the miniaturization of many technologies, including computers and satellites—according to researchers at the University of California-Irvine.

“If you can see a single molecule in action, then you can intervene, control and direct what it does,” says V. Ara Apkarian, director at UC-Irvine’s Chemistry at the Space-Time Limit, one of three National Science Foundation’s Centers for Chemical Innovation.

“We’re starting to image the motion of molecules, and we’ve developed methods that sense motion on length scales smaller than the nucleus of an atom.”

A video-capture rate of 1 million billion frames per second (the standard TV video rate is about 30 frames per second) is required for molecules, and each frame must be taken with magnification 10,000 times higher than the best existing optical microscope.

Observing individual molecule behavior will demystify important aspects of chemistry, scientists believe.

Out of billions of molecules the same shape and size, only particular ones will ignite a desired reaction. For example, certain gold particles catalyze the conversion of carbon monoxide to carbon dioxide, but which ones and how remain subjects of debate. Knowing this would enable chemists to design and manufacture more efficient, environmentally friendly catalysts.

“In many cases, the ensemble is not important, but the individual is,” Apkarian says. “This also happens in real life. In a group of people, one person’s action may determine the course of the whole. If we only look at average behavior, we will miss how an outlier controls the fate of everyone involved.”

Single-molecule devices such as transistors, radios, and chemical sensors are currently being developed. “This is engineering at the ultimate atomistic limit,” Apkarian says. “There’s no question the tools that enable the observation and manipulation of one molecule at a time will be the pillars on which the field of nanotechnology will be built.”

Researchers from Northwestern University and University of California at Santa Barbara contributed to the study, which is being funded by the National Science Foundation.

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