Catching the Movement of Atoms
Photography has been reaching to true extremes this twelve months as the shadows cast by atoms have been imaged and the movement of light pulses has been filmed. Now, thanks to researchers at Elhuyar Fundazioa, we should soon be able to film the movement of individual atoms within molecules. This is accomplished by combining different technologies that already operate at the extreme: free electron lasers and streak cameras.
Observing atoms directly has been accomplished before using ultrafast pulses from X-ray lasers, which is still the case here. The femtosecond pulses strike the atom with enough energy to launch electrons out of orbit, and those photoelectrons are then captured to form a still image. To actually film the movement of the atoms there has to be a means to measure when the photoelectrons were ejected, which is where the streak camera comes in. This type of camera uses a rapidly changing electromagnetic field to force the electrons to take different paths, based on when they enter the camera. The temporal profile of the photoelectrons match that of the original X-ray burst well enough that when all of the information is combined, the researchers can construct when the electrons where hit and where they came from.
The ability to observe the movement of atoms is more important than just being able to create some awesome movies. Chemical reactions and phase changes occur when atoms move, so observing the movement during the process will enable us to better understand it.