Oxford scientists claim to have created a transparent form of aluminum by bombarding the metal with the world’s most powerful soft X-ray laser. The substance is nearly transparent to extreme ultraviolet radiation and is the latest addition to a growing list of exotic states of matter.
Crossing over from science fiction to fact, 'transparent aluminum' was an idea featured in the movie Star Trek IV. The creation of the real material, however, has implications for areas as diverse as planetary science, astrophysics, and nuclear fusion.
To create the exotic matter, an international team of researchers led by Oxford University scientists used a short pulse from the FLASH laser to ‘knock out’ a core electron from every aluminum atom in a sample without disrupting the metal’s crystalline structure. They report that this turned the aluminum nearly invisible to extreme ultraviolet radiation. Pictured left is an experimental set-up at the FLASH laser facility used to discover the exotic material.
''What we have created is a completely new state of matter nobody has seen before,’ said Professor Justin Wark of Oxford University’s Department of Physics, one of the authors of a paper detailing the findings in this week’s Nature Physics.
‘Transparent aluminum is just the start. The physical properties of the matter we are creating are relevant to the conditions inside large planets, and we also hope that by studying it we can gain a greater understanding of what is going on during the creation of 'miniature stars' created by high-power laser implosions, which may one day allow the power of nuclear fusion to be harnessed here on Earth,’ Wark added.
To make it possible, the discovery required a new source of radiation that is ten billion times brighter than any synchrotron, a type of particle accelerator, in the world. The FLASH laser, based in Hamburg, Germany, was up to the task. It generated extremely brief pulses of soft X-ray light, each one more powerful than the output of a power plant that provides electricity to a whole city. The researchers directed all this power down into a spot with a diameter less than a twentieth of the width of a human hair. The result was the aluminum turning transparent for an extremely brief period – an estimated 40 femtoseconds, or one quadrillionth of a second.
This discovery demonstrates that such an exotic state of matter can be created using very high power X-ray sources, claims the Oxford team. Professor Wark added:
What is particularly remarkable about our experiment is that we have turned ordinary aluminum into this exotic new material in a single step by using this very powerful laser. For a brief period the sample looks and behaves in every way like a new form of matter. In certain respects, the way it reacts is as though we had changed every aluminum atom into silicon: it’s almost as surprising as finding that you can turn lead into gold with light!
Source: University of Oxford