AN APPARATUS FOR ISOTOPIC RATIO MEASUREMENT IN UF5 FORMED BY INFRAREDMULTIPHOTON DISSOCIATION OF UF6 IN MOLECULAR-BEAM

A Separation factor was measured in isotopically selective infrared mu ltiphoton dissociation (IRMPD) of supercooled UF6 in a supersonic expa nsion by multiphoton ionization (MPI) and time-of-flight mass spectrom etry (TOFMS). A pulsed free-jet nozzle was used to generate a UF6-mole cular beam seeded in Ar (similar to 10(-7) Torr in UF6 partial pressur e). Two-frequency p-H-2 Raman laser beams around 16 mu m were used for the dissociation of UF6 under collisionless conditions in the molecul ar beam where the flow velocity for UF6 is about 500 m/s. The U-235/U- 238 isotopic ratios in nascent UF5 photoproducts were determined by se lective MPI of UF5 at 532 nm followed by TOFMS with a mass resolution as high as 1200. A separation factor of about 2 was observed under the experimental conditions chosen for the demonstration of this method.