By expanding high-purity helium gas at high pressure through a small cryocooled nozzle into vacuum, one obtains a supersonic beam of liquid nanodroplets He_n (n~10³-10⁶). These droplets have sub-Kelvin internal temperatures and are even superfluid. They are also very efficient at in-flight capture of impurity atoms and molecules. As a result, they can function as "nano-cryostats" for molecular beam spectroscopy. We are studying

• Formation, behavior, and spectroscopy of alkali metal clusters on the helium droplet surface
• Attachment of slow electrons to impurities in and on the droplets
• Fragmentation and mass spectrometric patterns of amino acid, water, and other molecules picked up by the droplets
  

This project is carried out in collaboration with Prof. Curt Wittig.

Nanodroplet beam apparatus