Comment Re:Scanning Tunneling Electron Microscope (Score 5, Informative) 304
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.
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.
