The transient changes in UV absorbances of the vibrationally excited UF6 at 220-330 nm were investigated. UF6 was excited by pulsed CO2 laser-pumped SF6 by a vibrational-vibrational energy transfer process. Under static conditions, the influences of CO2 laser fluence and SF6 and UF6 partial pressure upon the UV absorption changes were measured. For a 2.0 torr SF6 and 2.0 torr UF6 mixture and at laser pulsed energy of 160 ?10 mJ, the UV absorption spectrum of vibrationally excited UF6 showed existence of 4 absorption peaks at 240, 248, 290, and 313 nm, resp. It may be related to the UV absorption of higher vibrationally excited UF6.

Key words: ABSORPTION SPECTROMETRY, URANIUM ISOTOPES, SPECTROGRAPHIC ANALYSIS, EXCITED STATE, CO2 LASER, ISOTOPE SEPARATION, ULTRAVIOLET RADIATION, URANIUM HEXAFLUORIDE, LASER CHEMISTRY, VIBRATIONAL STATE