Ivan O. Antonov, Michael C. Heaven Emory University, Department of Chemistry 1515 Dickey Drive, Atlanta GA 30322

 Nuclear waste disposal and reprocessing

(I. Infante et al. JCP, 127, (2007)) DG 1/2 = 914 cm -1 (Ne), 776 cm -1 (Ar) Ground state configuration 5f7s  5f 2 (Zhou, Andrews, Ismail & Marsden JPCA, 104, 5495 (2000)) 5f7s 5f 5/2 5f 7/2 Ω=2 Ω=3 Ω=4 How widely are the 3 Φ u and 3 H g states split???

UO 2 exhibits delayed ionization near the IP threshold Extremely large density of states!!! ZEKE spectrum of UO 2 + is highly congested (Merritt J.M., Han J., Heaven M.C., JCP, 128, (2008))

 Dispersed fluorescence from previously observed electronically excited states  1+1’ REMPI with first photon in red-NIR  SEP spectroscopy

1064 nm, 26 mJ He with 0.1% O2 Ablation Probe laser(s) PMT MCP Probe laser TOF mass-spec Oscilloscope Monochromator Ablation laser

X 3Φg3Φg Emission Excitation V=1

X 3Φg3Φg Excitation 2 nd order of monochromator Emission

X 3Φg3Φg Tunable ND:YAG pumped dye laser t Fluorescence SEP allows probing the ground state SEP on UO2 failed due to state mixing!

X UO 2 + +e Tunable ND:YAG pumped dye laser 248 nm KrF

(I. Infante et al. JCP, 127, (2006)) ExperimentIHFSCC 40 e – cm -1 1 u at cm -1 2 u at cm -1 4 u at cm cm -1 2 u at cm cm -1 4 g at cm cm -1 0 g at cm cm -1 1 g at cm cm -1 2 g at cm cm -1 1 g at cm cm -1 1 g at cm -1 or 5 g at cm -1

 UO2 molecule was studied by REMPI at – cm -1 and by dispersed fluorescence on cm -1 and cm -1 transition  New excited states were found and preliminarily assigned at cm -1, 7400 cm -1 and cm -1 region  Excited state mixing phenomena is responsible for severe line broadening and background signal; It prevents from obtaining rotationally resolved spectra of UO2

 1+1’ REMPI with OPO/OPA system in mid-IR X UO 2 + +e OPO/OPA Tunable ND:YAG pumped dye laser at ~ nm

Vladimir E. Bondybey for help with experiment Group members: Beau Barker, Jiande Han, Keith Freel and Humayun Kabir Prof. Michael Heaven DOE for funding!!!