X-Ray and Visible Light Combine to Studying How Light Affects AtomsCategory: Science & Technology
Posted: August 31, 2012 12:13PM
To study the world of atoms researchers have to be very clever as the energies required to observe atoms can also so change the system, that a lot of information is lost. For example, X-rays have to be used to target where an atom is in a crystal, but will impart so much energy to its electrons that the core and valence electrons cannot be distinguished. Now researchers at Berkeley Lab have used the visible light with an X-ray pulse to get at that information.
Not all electrons that orbit an atom are equal as their differing energy levels dictate how they behave. Only those the furthest out in the valence orbits will interact with other atoms, while the core electrons stay where they are. Typically, hard X-rays hitting an atom will toss all of these electrons away with so much energy you cannot distinguish the valence electrons from the more plentiful core electrons. By adding the optical laser light though, the researchers gave the valence electrons a charge that the X-rays scatter from. This scattering changes the frequency of the X-rays enough to be measured.
This is the first time researchers have directly measured how an optical signal affects valence electrons, which are responsible for chemical bonds, at the scale of individual atoms. The experiment was done on a piece of diamond, a well understood crystal, but the hope is to see it done on other materials, like those involved with photosynthesis, though it may be some time before that happens.