News source: http://news.mit.edu/

State-of-the-art atomic force microscopes (AFMs) are designed to capture images of structures as small as a fraction of a nanometer — a million times smaller than the width of a human hair. In recent years, AFMs have produced desktop-worthy close-ups of atom-sized structures, from single strands of DNA to individual hydrogen bonds between molecules.

But scanning these images is a meticulous, time-consuming process. AFMs therefore have been used mostly to image static samples, as they are too slow to capture active, changing environments.

Now engineers at MIT have designed an atomic force microscope that scans images 2,000 times faster than existing commercial models. With this new high-speed instrument, the team produced images of chemical processes taking place at the nanoscale, at a rate that is close to real-time video.

In one demonstration of the instrument’s capabilities, the researchers scanned a 70- by-70-micron sample of calcite as it was first immersed in deionized water and later exposed to sulfuric acid. The team observed the acid eating away at the calcite, expanding existing nanometer-sized pits in the material that quickly merged and led to a layer-by-layer removal of calcite along the material’s crystal pattern, over a period of several seconds.

Kamal Youcef-Toumi, a professor of mechanical engineering at MIT and SASTA’s Board member, says the instrument’s sensitivity and speed will enable scientists to watch atomic-sized processes play out as high-resolution “movies.”

“People can see, for example, condensation, nucleation, dissolution, or deposition of material, and how these happen in real-time — things that people have never seen before,” Youcef-Toumi says. “This is fantastic to see these details emerging. And it will open great opportunities to explore all of this world that is at the nanoscale.”

The group’s design and images, which are based on the PhD work of Iman Soltani Bozchalooi, now a postdoc in the Department of Mechanical Engineering, are published in the journalUltramicroscopy. Co-authors include former graduate student Andrew Careaga Houck and visiting scholar Jwaher AlGhamdi. Read more >>