Isotope sepn. was demonstrated following the selective IR laser-induced photodissocn. of van der Waals clusters in a free jet. Irradn. of a natural abundance mixt. of SF6 isotopomers dild. in Ar with a 20-W cw CO2 laser gave overall enrichment factors >1.1. By adjusting the wavelength one can either enrich or deplete the center of the free jet in any one of the S isotopes.