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Title Reaction of fluorine atoms with monomeric and polymeric uranium pentafluoride
Creator/Author Lyman, J.L. ; Holland, R.
Publication Date1987 Aug 27
OSTI IdentifierOSTI ID: 5916043
Other Number(s)CODEN: JPCHA
Resource TypeJournal Article
Resource RelationJ. Phys. Chem. ; Vol/Issue: 91:18
Research OrgLos Alamos National Lab., NM
Subject400702 -- Radiochemistry & Nuclear Chemistry-- Properties of Radioactive Materials ;400500 -- Photochemistry; FLUORINE-- CHEMICAL REACTIONS;FLUORINE-- PHOTOLYSIS;URANIUM PENTAFLUORIDE-- CHEMICAL PREPARATION;URANIUM PENTAFLUORIDE-- CHEMICAL REACTIONS;URANIUM PENTAFLUORIDE-- PHOTOLYSIS; CHEMICAL REACTION KINETICS;EXPERIMENTAL DATA;LASERS;MEDIUM TEMPERATURE;MONOMERS;POLYMERS;QUANTITY RATIO;TIME DEPENDENCE
Related SubjectACTINIDE COMPOUNDS;CHEMICAL REACTIONS;DATA;DECOMPOSITION;ELEMENTS;FLUORIDES;FLUORINE COMPOUNDS;HALIDES;HALOGEN COMPOUNDS;HALOGENS;INFORMATION;KINETICS;NONMETALS;NUMERICAL DATA;PHOTOCHEMICAL REACTIONS;REACTION KINETICS;SYNTHESIS;URANIUM COMPOUNDS;URANIUM FLUORIDES
Description/Abstract The authors have measured the room-temperature rate constants for formation of UF/sup 6/ from the reaction of fluorine atoms with UF/sub 5/.^The rapid growth of UF/sub 5/ clusters (polymers) from the nascent monomeric species complicates the rate measurements.^The ratio of the rate of UF/sub 5/-dimer formation to the rate of monomer-fluorine recombination is insensitive to the cluster formation.^That ratio, k/sub mm//k/sub rm/ = 5.0 +/- 1.0, is the authors most reliable experimental result.^It, along with additional experimental data, give k/sub rm/ = 8.0 x 10/sup -12/ cm/sup 3/ molecule/sup -1/ s/sup -1/ and k/sub mm/ = 4.0 x 10/sup -11/ cm/sup 3/ molecule/sup -1/ s/sup -1/.^To obtain the dependence of reaction rates on s, the average UF/sub 5/ polymer size, the authors assumed that the rates were proportional to the collision rate.^The derived rate constants were k/sub pp/ = k/sub mm/s/sup 1/6/ cm/sup 3/ molecule/sup -1/ s/sup -1/ for cluster growth and k/sub rp/ = 4.1 x 10/sup -14/(1 + 2s/sup 1/3/)/sup 2/ cm/sup 3/ molecule/sup -1/ s/sup -1/ for reaction of fluorine atoms with polymeric UF/sub 5/.^The experimental procedure was to photolyze both F/sub 2/ and UF/sub 6/ in helium diluent with a KrF excimer laser to produce UF/sub 5/ and an excess of fluorine atoms.^This allowed the slower recombination reactions to compete with polymerization.^They monitored the transient concentration of UF/sub 6/ with an ultraviolet probe beam at 215 nm.^The recombination of fluorine atoms with UF/sub 5/ monomer is substantially faster than recombination with the polymer.
Country of PublicationUnited States
LanguageEnglish
FormatPages: 4821-4826
System Entry Date2001 May 13

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