Scientists Create Aluminum That Is Transparent in X-Rays

What a few years ago seemed like a thing of science-fiction, as viewed in the popular show Star Trek, has recently been proven by German scientists to exist in real-life as well. Scientists at the FLASH facility, in Hamburg, have created a form of transparent aluminum, albeit only visible in X-ray wavelengths. The achievement was made possible through the use of an extremely energetic laser, able to generate ten million gigawatts of power per square centimeter on a thin piece of aluminum foil.

The monstrous amount of energy had a direct effect on the metal's own internal structure. In the average piece of aluminum, a lattice of ions creates the material, while a large number of electrons permeate the entire ensemble, giving it cohesion. When the high energy of the laser struck in a pulse, one electron of each atom was stripped away, at a speed too high to allow for it to be replaced, as is usually the case. Therefore, the photons that followed were met with a lot more resistance, and were able to pass through the foil without problems. When you look at this phenomenon in X-rays, it appears as if the aluminum has suddenly become transparent.

However, there is a problem with the new material. “As soon as you make it, the stuff blows up,” University of Oxford expert Justin Wark explains. This happens for a very simple reason. After the laser pulse begins to hit the foil, and the electrons are ripped apart, only a few nanoseconds pass by before the energy hitting the electrons is transferred to the ions, which lose their connections to each other violently. However, that doesn't change the fact that, for a short amount of time, a new state of matter exists.

Wark details that the matter thus obtained is just as dense as any solid material, but that it also features extremely hot temperatures. He believes that similar types of substances exist at the core of planets, where immense heat causes even solid materials to behave like liquids, even though they maintain the same density. “That is the sort of matter you would get towards the centre of a giant planet,” the expert says, quoted by NewScientist.

Publishing the findings in the latest issue of the scientific journal Nature Physics, the team also shows that, by using more advanced lasers, such as the one at the Linac Coherent Light Source, in Stanford, California, more properties of this very hot and dense state of matter could be experimentally determined. This class of lasers is more powerful than the one the team used, and is able to generate X-rays at higher energies, which could give scientists better conditions to observe what is going on inside the transparent, solid metal.