PRODUCTION, CHARACTERIZATION, AND SCATTERING OF A BEAM OF SULFUR MONOXIDE RADICALS - THE SO NOBLE-GAS INTERACTIONS

An intense and stable continuous beam of SO radicals has been produced with a microwave-discharge source operating in the Torr range in mixt ures of SO2 with various gases. The free-radical beam emerging from th e plasma source is velocity analyzed by a mechanical velocity selector and detected by a quadrupole mass filter. Stern-Gerlach magnetic anal ysis shows SO radicals mainly in the electronic ground state (3) Sigma (-) with a rotationally hot distribution and provides an upper limit ( less than or equal to 7%) on the concentration of electronic metastabl e states. Total integral cross-section measurements as a function of v elocity in the range 0.9-2.4 km.s(-1) for the scattering of ground-sta te SO radicals by Ne, Ar, and Kr have also been performed. The analysi s of experimental data (cross sections and their velocity dependence, which exhibits glory interference patterns) allows a characterization of the interaction potential features for the investigated systems. Us e of a correlation rule leads to an estimate of the average polarizabi lity of the SO molecule and also of the potential features for SO-He a nd SO-Xe.