Transparent aluminium

Transparent aluminium is a state of aluminium achieved by bombarding a thin (50 nm) Al foil with soft X-ray laser radiation (wavelength 13.5 nm). The short laser pulse knocks out a core L-shell electron from every aluminium atom without breaking the crystalline structure of the metal making it transparent to soft X-rays of the same wavelength.[1] This phenomenon is called saturable absorption. The thus produced transient state of aluminium is as dense as ordinary matter but can only exist for an extremely short period of time, as the energy required to maintain the high temperature which would be necessary to hold it in this state would be enormous. To create transparent aluminium, more power than is used by an entire city had to be focused into a dot with a diameter of less than one-twentieth of a thickness of a human hair, and then could only maintain the transparent state for 40 femtoseconds.[1][2].

References

1. ^ a b "Transparent Aluminum Is ‘New State Of Matter’". sciencedaily.com. July 27, 2009. http://www.sciencedaily.com/releases/2009/07/090727130814.htm. Retrieved 29 July 2009.
2. ^ Nagler, B.; Zastrau, U.; Fäustlin, R. R.; Vinko, S. M.; Whitcher, T.; Nelson, A. J.; Sobierajski, R.; Krzywinski, J. et al. (2009). "Turning solid aluminium transparent by intense soft X-ray photoionization". Nature Physics 5: 693. doi:10.1038/nphys1341.