Atoms Receive 'Movie Star' Treatment

Roland Piquepaille writes "A news release from the University of Toronto (U of T) says that a team of chemists has successfully captured images of atoms during the melting of aluminum. "Chemists at the University of Toronto have captured atom-scale images of the melting process-revealing the first images of the transition of a solid into a liquid at the timescale of femtoseconds, or millionths of a billionth of a second. The result is an unprecedented "movie" detailing the melting process as solid aluminum becomes a liquid." Can this be useful for you? Probably not. But these chemists think they have a new valuable tool which will allow them to make atomic movies of other chemical reactions. This summary contains more details and additional references."

Comments

Worthless

[GoRK]

This thread is worthess without pics.

Seriously, this is cool, but the whole thing is about photos that don't seem to be available anywhere yet except in the magazine.

One has to wonder

[Zerth]

Will the aluminum atoms be cancelling their appearance on Letterman?

Hope they weren't underage... What is the age of consent for aluminum, anyway?

Oh, there are pictures

[Laplace]

You just can't see them. They're tiny. The size of atoms.

odd...

[cagle_.25]

The aluminum melted in an astonishingly short time-within 3.5 picoseconds.

The article seems to hint that melting processes in general are equally short. But of course, melting on the macroscale does not occur in picoseconds. If you take an ice cube and place it in a 20 deg. C room, it will take a good while to melt. It's easy to see why: it takes time for individual atoms in the solid phase to acquire enough energy to shake free.

The conclusion I draw from the experiment is not that melting occurs rapidly in general, but rather that there is no "in between" transition state between solid and liquid. Now that's cool. It would be neat if they could extend this experiment to substances that have two different liquid forms, like sulfur and see whether there is an intermediate state between them. SiO2 glass might be particularly interesting. We could also investigate dimerizations and all manner of things ... hmmm... to quote the article,

"Chemists think of reactions in terms of atoms moving around as bonds are broken and formed," says Jason Dwyer, a graduate student in Miller's laboratory and a co-author of the paper. "It is one of the dreams of chemistry to be able to actually watch that as it happens, and we now have a technique that lets us do that."

"movie"

[Bowling Moses]

There's a reason for the quotation marks. The researchers did obtain a movie of sorts, in that they repeated their basic experiment to get different timepoints in the melting process. However the frames making up the movie are electron powder diffraction (EPD) images. What you get is basically a pattern of rings centered like a bullseye, and the spacings between the different rings can tell you information about the material like how the atoms are configured. Put in the time component from several images and you can get (in this instance) a "movie" of aluminum melting.

I tried to find a free EPD image, but the closest thing I found was xray powder diffraction, with fake color--what you get from a diffraction image is greyscale. Anyway, it's a similar experiment, except the material is bombarded with xrays instead of electrons.

Pictures

[Necro Spork]

They have picture and pretty graphs here! Happy now?
http://www.sciencemag.org/cgi/content/full/3 02/564 9/1382