Mass spectrometric and electron impact study of the spatial separation of mixtures of butane and argon in a pulsed supersonic jet

The spatial distribution of a pulsed molecular beam of butane seeded in Ar has been monitored by a movable mass spectrometer. The same beam has also been subjected to electron impact measurements, which provide additional information on the properties of the beam. Both measurements were carried out over a wide range of stagnation pressures. Substantial separation of gases, both across and along the jet, was observed. Some other mixtures were also tested for the existence of the separation effect. In several cases, there was no correlation between the value of the separation effect and the ratio of molecular masses of the mixed gases. These phenomena are accounted for by the formation of large clusters of the carrier gas, with guest molecules embedded in them.