A team headed by Frank Stienkemeier at The University of Freiburg’s Institute of Physics and Marcel Mudrich at the University of Aarhus in Denmark has observed the ultrafast reaction of nanodroplets of helium after excitation with extreme ultraviolet radiation (XUV) using a free-electron laser in real time.
Lasers generating high-intensity ultrashort XUV and X-ray pulses give researchers new options for investigating the fundamental properties of matter in great detail. In many such experiments, material samples in the nanometer range are of particular interest.
Some scientists use helium droplets no larger than a few nanometers as a means of transporting and studying embedded molecules and molecular nanostructures. Helium droplets are ideally suited for this purpose because they possess extraordinary properties. At a temperature of only 0.37 K, they move without friction and are thus considered superfluids. Moreover, helium droplets usually are inert to the embedded molecules’ chemical processes and are completely transparent to IR and visible light.