Slashdot Mirror
Lead Atoms Imaged During Phase Change
fsh writes "José Gómez-Rodríguez and company from the Madrid Autonomous University have successfully imaged the phase change of a lead crystal from 45K to 135K. They built their very own variable temperature scanning-tunneling microscope, capable of continuously scanning an area 20nm square throughout a 100K temperature jump. This was a surface phase change, but their technique will hopefully pave the way for imaging other phase changes, like solid to liquid. Check out the movie."
You did, eh, RTFA? You're the first poster and the site hasn't been /.ed yet. So you have no excuse From TFA:
"One case where defects matter is the behavior of surface phase transitions. A layer of tin atoms on a germanium surface forms a flat lattice, but at temperatures below about 150 Kelvin--for reasons that aren't entirely clear--the tin layer spontaneously corrugates to form a new structure, or phase, with one atom out of every three moving away from the substrate."
If you don't know why/how of these processes, you can't predict or control them. Thus engineering with any sort of multi-material boundaries and surfaces at low temperatures loses some precision and purity due to not-fully-understood effects.
As for questions of when we'd ever use nanoscale materials like this, think semiconductors. All semiconductors rely on doping one substance (like silicon) with another like germanium or aluminum (or pretty much any Group III or V elements). Yes, this is particular research is more for theoretical support, but various things tie in all over the place. In any research, the more general knowledge you have, the more particular applications you'll be able to come up with.
The ability to be able to closely watch individual atoms perform their trickery and as a result prove older theories/bring up new questions allows chemists/physicists to make new advances in the field of nanotechnology, as an example. Funny things happen on this small a scale, and there are forces at work which don't manifest themselves in the same way on the macroscopic scale - as such these systems that can now be (indirectly) observed are harder to predict mathematically. Knowing how they interact during phases changes can help to understand how they can be controlled.