X-ray pulses make atomic oscillations

Researchers from the Max Born Institute in Berlin, Empa and the US National Institute of Standards and Technology (NIST) have, for the first time, been able to observe minute, ultrafast atomic oscillations in a crystal lattice with the help of a new experimental technique. These oscillations, which are triggered by light pulses, are based on a physical effect - Raman scattering - which was postulated about 100 years ago. The Austrian theoretical physicist Adolf Smekal postulated a physical effect in 1923 which predicted that, following the scattering of light from atoms, molecules or crystals, energy would be transferred between the light quanta - photons - and the atoms or molecules being targeted, thereby causing a change in the frequency (and therefore the energy) of the light scattered by the collision. While considering the ramifications of this effect, Smekal assumed that would never be possible to observe this sub-microscopic process as it would take place in just a few femtoseconds (10^-15 s). Nevertheless, just a few years later in 1928, the Indian physicist (and later Nobel laureate) Chandrasekhar Raman was able to demonstrate the frequency shift efect for the first time experimentally. Raman scattering, as the process is known today, forms the basis of one of the most important physicochemical methods for investigating material properties. It is frequently used at Empa, for purposes such as studying the structure of molecules and solid matter, for the characterisation of thin-films, and for the detection and quantification of chemical substances in gases and liquids.