Inhibition of formation of SF6 molecular clusters in a free supersonic expansion

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Abstract
In this work we present experimental results on the inhibition of formation of sulfur hexafluoride molecular clusters in a free supersonic expansion, due to resonant absorption of intense radiation from a pulsed CO2 laser. The spatial energy distribution of the molecular beam in the transverse direction was measured with a pyroelectric detector with and without incident radiation. A skimmer placed in the collisional region of the expansion causes a second expansion of the molecular beam which is more divergent when these molecules are vibrationally excited by a CO2 laser beam perpendicularly crossing the molecular beam before the skimmer. This is due to the inhibition of formation of molecular clusters by the CO2 laser beam which leads to a lower average mass for the expanding beam particles. In a molecular beam with isotopic species, a selective inhibition of formation of clusters would lead to different spatial distribution for different isotopes in the molecular beam.