[scienceofscience (OP)]

http://www.dailygalaxy.com/my_weblog/2010/05/-flash-laser-leads-to-discovery-of-new-state-of-matter.html [nofollow]

[CliffordK]

It is an interesting study.  But, not quite reminiscent of Star Trek.

Like a scene out of Star Trek, Oxford scientists have created a transparent form of aluminium
[...]
a short pulse from the FLASH laser ‘knocked out’ a core electron from every aluminium atom in a sample without disrupting the metal’s crystalline structure.
This turned the aluminium nearly invisible to extreme ultraviolet radiation.
[...]
The Oxford team ... focused all this power down into a spot with a diameter less than a twentieth of the width of a human hair. At such high intensities the aluminium turned transparent.
[...]
the invisible effect lasted for only an extremely brief period - an estimated 40 femtoseconds

So, it is only "invisible" with respect to light that is not visible to humans anyway.  It is focused in a tiny spot, and doesn't even last a second.

Interesting...  perhaps.

It sounds like they've just found a new way to ionize matter.

Loosing the electrons, for those brief few femtoseconds, the sample would be strongly electro-positive.  Since Aluminum is a good conductor, the effect is very transient.

Would bombarding an insulator be more stable?

Do you get the same effect from simply rubbing a balloon in your hair...  with a lot less expense?

[CliffordK]

One should note, of course, there are several aluminum oxide and aluminum oxynitride crystals and ceramics that are transparent, are larger than a hair, and last for more than a second.

[evan_au]

It sounds like they tuned the X-Ray laser to the energy level emitted when the electron of an aluminium atom falls down to one of the inner-shells.

Exposing aluminium to this X-Ray wavelength will promote all the inner-shell electrons to a higher shell.

When all the inner-shell electrons had been promoted (forming a population inversion), the X-Rays of that frequency will not be so strongly absorbed, and the material will be more transparent to X-Rays of that frequency.

As soon as you turn off the laser, there will be nothing to maintain the population inversion, and the electrons will quickly fall back to their lower-energy state.

Of course, after you have formed the population inversion, there will be no electrons with exactly the right energy to move to a different level - but you could easily kick an outer electron right out of the atom, creating a "hot" electron in the conduction band.

Speaking of hot, the aluminium sample would probably heat up considerably, when exposed to a pulse of X-Rays. Not good for building a giant fishtank for transporting endangered whales.

[CliffordK]

Exposing aluminium to this X-Ray wavelength will promote all the inner-shell electrons to a higher shell.

Thanks Evan,

So it is essentially doing what every Atomic clock does by promoting the atoms to the next higher energy level, but on this case doing it on a very massive scale in a solid rather than a gas.