- Formation and characterization of HUF and DUF in solid argon
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Reactions of laser-ablated U atoms with HF and DF in condensing and solid rare gas produce HUF and DUF as the major new products based on close agreement between observed and calculated vibrational frequencies and deuterium shifts for U-H and U-F stretchi
- Vent-Schmidt, Thomas,Hunt, Rodney Dale,Andrews, Lester,Riedel, Sebastian
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p. 3863 - 3865
(2013/07/25)
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- Matrix IR spectra of the products from F2, ClF, and Cl2 reactions with pulsed-laser evaporated uranium atoms
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Pulsed Nd:YAG laser ablated uranium atoms were codeposited with F2 and excess Ar onto a CsI window at 12 K. Infrared spectra revealed the presence of several uranium fluorides including the previously characterized UF4, UF5, and UF6. Lower laser energy favored new absorptions at 400, 446, 496, and 561 cm-1. These product absorptions increased stepwise during annealings which permitted diffusion and reaction of the fluorine. Similar studies with ClF produced the above absorptions plus a new band at 554 cm-1 which is tentatively assigned to ClF2-. The first bands appearing at 400 and 446 cm-1 are assigned to UF and UF2, respectively. The 496- and 561-cm-1 bands are tentatively assigned to UF3 and F3-, respectively. Finally, uranium atoms were reacted with Cl2. In addition to several absorptions due to UCl4, a new doublet at 312 and 308 cm-1 is assigned to UCl2.
- Hunt, Rodney D.,Thompson, Craig,Hassanzadeh, Parviz,Andrews, Lester
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p. 388 - 391
(2008/10/08)
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- Thermochemical properties of the gaseous lower valent fluorides of uranium
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High temperature gaseous equilibria involving the lower-valent uranium fluorides UF, UF2, UF3, and UF4 were studied by mass spectrometry, and reaction enthalpies and entropies with estimated uncertainties of +/-2 kcal/mol and +/-2 cal/deg mol were derived solely from the temperature coefficients of reaction equilibrium constants.These results yield the following bond dissociation energies at 298 K in kcal/mol: Do(F3U-F) = 148.2; Do(F2U-F) = 149.0; Do(FU-F) = 136.5; and Do(U-F) = 157.5.The sum of these values is compatible with the heat of atomization of UF4(g) evaluated from independent source.A value of Do(F3U-F) derived from electron impact measurements agrees well with the equilibrium data.The reaction entropy data indicate that the electronic entropies of UF, UF2, and UF3 are comparable to that of atomic uranium in the same temperature range, and provide a basis for estimating the total thermodynamic functions of these species.Experimental entropies obtained for UF4 indicate the likelihood of a distorted tetrahedral structure of effective C2v symmetry.The results provide sufficient information for predicting the equilibrium composition of the gaseous U-F system over a wide temperature range.
- Lau, K. H.,Hildenbrand, D. L.
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p. 2646 - 2652
(2007/10/02)
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