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The Submillimeter Spectrum of UO Jennifer A. Holt Christopher F. Neese Frank C. De Lucia June 17, 2014
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Experimental Setup
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High Temperature Furnace Vacuum Water cooled shield Radiation Shields Furnace Tube Power Supply
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Production of NdO vs UO High temperature decomposition of Nd 2 O 3 – ~2200K – Run times of ~3 hours UO from mixed metal and oxide – Starts with mixed metal and oxide – Highly aggressive to furnace – Short runtimes of ~20 minutes – Temperature ~2000K
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Experimental Changes for UO Graphite tube with tungsten liner and Y 2 O 3 painted coating – Increased furnace durability and runtimes – Increased S/N Sample consists of U metal with UO 2 Powder – Materials mixed and pressed into pellet – Pellet placed in the center of the furnace tube
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Graphite Furnace Tube
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Spectral Coverage
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Example Lines
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(1)3(v=0)R31
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Spectroscopy of UO vs NdO NdO has 3 isotopes with similar natural abundance, UO has one. UO has a second low lying electronic configuration. J. Chem. Phys. 124, 184317 (2006) © 2006 American Institute of Physics Kaledin et al., J. Mol. Spectr. 164, 27-64 (1994)
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UO LFT UO is a Hund’s case C molecule, (minimal information). LFT gives an alternate description with a U 2+ cation perturbed by a O 2- ligand. U 2+ has two low lying electronic configurations: [5f 3 7s], [5f 2 7s 2 ]. Approximate quantum numbers J f and J a from SO and J-J coupling. LFT allows for the calculation of an energy map of the low lying electronic states. Hund’s Case C Coupling
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Energy Map Kaledin et al., J. Mol. Spectr. 164, 27-64 (1994)
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Line Assignments Vibronic StateB (GHz)D (KHz)σ ν (KHz) (1)3(v=0)9.831265.8688626.2 (1)3(v=1)9.790565.906747.35 (1)3(v=2)9.750225.9397939.2 (1)3(v=3)9.710005.9287663.7 (1)5(v=0)9.893496.0383843.6 (1)5(v=1)9.853546.068119.6 (1)5(v=2)9.824755.4080240.4 (1)5(v=3)9.798895.5104532.3 X4(v=0)9.9927810.2945470 X4(v=1)9.896096.96244254 X4(v=2)9.840155.761915.9 (2)4(v=0)10.37782.14331372 (2)4(v=1)10.38895.81611172 [5f 3 7s] [5f 2 7s 2 ]
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UO Line Stats 285 observed lines from 510 GHz to 652 GHz 13 series identified and assigned 3 series identified, but not assigned 200 unassigned lines
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Ongoing work Continue line assignments Dunham fits over vibrational states
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Acknowledgements Michael Heaven Ivan Medvedev We would also like to thank the Missile Defense Agency and the Army Research Office for their support of this work
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Supplemental Slides
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Material Properties (W) Highest melting point metal: 3695K Very hard and brittle Difficult to work Does not spot-weld with any equipment we have Moderately expensive
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Material Properties (Mo) Melting point 2896K Softer and more ductile than tungsten Can spot-weld with difficulty Fairly inexpensive
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Material Properties (Ta) Melting point 3290K Very ductile and easy to work Easily spot-welds Expensive
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Material Graphite (C) Sublimation point 3915K Machines easily, but very brittle Conductivity lower than metals, allows better electrical match to power supply Forms carbides with U at high temperatures Reacts with Y 2 O 3 at high temperatures
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Material Yttria (Y 2 O 3 ) Melting point 2698K Very stable chemically, holds up well to molten uranium Reacts with carbon at high temperatures Transparent in SMM region
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