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The Sharpest Object Ever Made
ultracool writes "Forget the phrase 'sharp as a tack.' Now, thanks to new University of Alberta research, the popular expression might become, 'sharp as a single atom tip formed by chemically assisted spatially controlled field evaporation.' Maybe it doesn't roll off the tongue as easily, but considering the researchers have created the sharpest object ever made, it would be accurate."
or the fact that the three moderation categories don't add to 100%.
You are aware that that list only shows the three mods with the most percentage?
Justice is the sheep getting arrested while an impartial judge declares the vote void.
Actually the Scanning Tunneling Microscope does not demand a single-atom tip (in the sense considered here). Rather, a reasonably sharp apex will have one atom which is slightly closer to the surface than its neighbors from which most of the electron tunneling takes place. A tip with a radius of curvature less than, say, 100 nanometers is generally sufficient for most STM usage. Problems can arise when the tip has multiple protrusions which are a roughly equal distance from the surface, especially when scanning larger surface features such as carbon nanotubes (as compared to an atomically flat surface).
That said, better tips mean better images, especially with larger surface features, and also lower field emission voltages, which means applications in electron microscopy and even flat-panel display technology.
That said, I've make single-atom tips (of the sort discussed in this article) in the lab on a regular basis over the past several years with an ion sputtering-based process, a technique that is not limited to tungsten (tungsten is hard, but oxidizes, meaning the tip will not withstand removal from an ultra-high vacuum environment). This is a very interesting technique, but claiming it to be the sharpest object ever made is certainly overstating the achievement.