The FT-IR spectra of clusters of UF 6 seeded in argon were measured in a continuous supersonic Laval nozzle flow. We observed absorption peaks of UF 6 clusters on both the red- and the blue-shifted sides of the monomer peak (around 627 cm - 1 ) at a temperature below 130 K. We assigned these peaks using calculated results on the frequency shifts and transition strength of the IR spectra of UF 6 clusters. Clusters as large as 10 in size were found to be formed under our experimental conditions. Vibrational predissociation of UF 6 clusters was observed after a single shot from a Raman laser tuned to a vibrational mode of the UF 6 clusters (614.8 cm - 1 ) in the Laval nozzle. We monitored the concentration of UF 6 monomers in the ground state with a diode laser spectrometer, and qualitatively interpreted the time-scale of the predissociation of the UF 6 clusters and the recombination of UF 6 monomers subsequent to the predissociation were deactivated with a time constant of about 0.3 μs via vibrational relaxation induced by collisions with carrier gas (argon) atoms. The recombination of UF 6 monomers produced by the vibrational predissociation competed with vibrational relaxation. The time constant of the recombination (about 6 μs) was found to be much larger than that of the relaxation.