Electronic Spectroscopy of UO2Cl2 Isolated in Solid Ar

Laser-induced fluorescence spectra have been recorded for uranyl chloride isolated in a solid At matrix Pulsed excitation was examined using a XeCl excimer laser (308 nm) and a dye laser operating in the 19 500-27 500 cm(-1) range. Several absorption and emission hand systems were observed The emission spectra were characterized by a nearly harmonic vibrational progression with a frequency of 840 cm(-1) starting at 20 313 cm(-1). The electronic absorption spectra were dominated by five hannonic vibrational progressions with frequencies of approximately 710 cm(-1). Comparisons with theoretical calculations indicate that all of tire transitions observed wercassociatcd with the UO2+2 subunit. They involved the promotion ofan electron from a bonding orbital to the mcial-cenicred 5f(delta) and 5f(phi) orbitals Band origins and vibrational constants for five excited slates were obtained Fluorescence was observed from the lowcst-energy excited state alone, regardless of the excitation wavelength. The decay curve was found to be bocxponeruial, with characierism decay lifetimes of 50 and 260 mu s