Dynamics of Correlated Materials
Dynamics of Correlated Materials
Emmy Noether Group Laurenz Rettig
Emmy Noether Group Laurenz Rettig

News Post
Highlight: Ultrafast Dynamics of Atomic Motion Viewed by the Electrons in Solids
Nov 2018

Capturing the motions of atoms in a so-called “molecular movie” is generally thought of as the Holy Grail for understanding chemical transformations or structural phase transitions in solids. However, atomic motion is not the whole story, as the forces driving these motions arise from details of the electronic structure and a gradient across a free energy landscape. Therefore, to obtain a complete picture of the processes driving structural changes, it is necessary to observe the dynamics of the electronic structure and track the temporal evolution of electronic states and their populations. By using femtosecond lasers to perform time- and angle-resolved photoemission spectroscopy, the changes of the electronic structure during the phase transition in indium nanowires on a silicon surface could be closely monitored, allowing a detailed reaction pathway to be extracted. This information combined with simulations of the electronic structure dynamics, made it possible to translate the electronic structure dynamics into a potential energy landscape and therefore extract not only the motion of atoms, but also the formation and breaking of chemical bonds during the phase transition. This provides a bridge between the languages of physics and chemistry for describing structural changes in both real and momentum space. Understanding how the transient electronic structure results in bond dynamics may in future allow the tailoring of chemical reactions and phase transitions via engineered light pulses.

“Beyond the molecular movie: Dynamics of bands and bonds during a photoinduced phase transition”
Science, Vol. 362, Issue 6416, pp. 821-825
DOI: 10.1126/science.aar4183
http://science.sciencemag.org/content/362/6416/821

  Artists view of the excitation and formation of chemical bonds along Indium nanowires (red balls)  on a Silicon(111) surface during the ultrafast photoinduced phase transition between the 8×2 and 4×1 structures. This real space view of atoms and bonds is complemented by detailed measurememets of the electronic  structure of electrons in their “momentum space” exhibiting the evolution of the band stuctrue providing a complete picture of the phase transition. © A.Lücke, Univ. Paderborn