The velocity distribution of clusters generated by inert gas condensation

The velocity distribution of sodium chloride clusters produced by inert gas condensation is determined by means of a mechanical chopping technique. It is found to be the same for all cluster sizes between 1 and more than 200 molecular units per cluster, ruling out the possibility of cluster mass separation by velocity filters. This is explained by an adiabatic expansion occuring during the cluster's exit from the condensation chamber into the high vacuum of the mass spectrometer.