Helium nanodroplets

By expanding high-purity helium gas at high pressure through a small cryocooled nozzle into vacuum, one obtains a supersonic beam of liquid nanodroplets Hen (n~103-106). These droplets have sub-Kelvin internal temperatures and are actually superfluid. They are remarkably efficient at capturing impurity atoms and molecules in-flight. As a result, they function as transparent, inert, superfluid "nano-cryostats" for spectroscopy, control of molecular assembly and reactions, generation of unusual prototype complexes and alloys, etc.


Nanodroplet beam apparatus