A mishap in the lab creates the world’s sharpest point.
Sometimes an accident isn’t such a bad thing. When physicist Bob Wolkow and his colleagues at the National Institute for Nanotechnology in Canada were trying to sharpen the tip of an electron microscope to enhance its resolution, they failed to notice a small but significant leak in its vacuum chamber. The hidden leak had allowed nitrogen to creep inside the machine and scrape away atoms on the dull tip.
The inadvertent result? The world’s finest pinpoint. “It was kind of magical to see it happen,” Wolkow says. The atom-wide tip, which is five millionths the width of the head of a pin, could help scientists better visualize exceptionally small objects such as cells and phenomena currently too small to see with even today’s best scopes.
Electron microscopes create highly magnified 3-D images by shooting electrons from an ultrafine tip. The finer the tip, the sharper the image. Scientists now rely on several sharpening techniques, one of which involves heating the tip, yet none of them has proven nearly as effective as Wolkow’s “magic” nitrogen. The gas, Wolkow has discovered, binds to tungsten atoms on the perimeter of the tip. When zapped with an electric field, the bound clumps fall away like the wood-graphite shavings of a freshly sharpened pencil. Using this technique, Wolkow was able to hone the tungsten to a single atom and increase the resolution of his scope by an impressive 20-fold.—Gregory Mone
Via: Popular Science