Reaction of fluorine atoms with monomeric and polymeric uranium pentafluoride

Journal Article · Thu Aug 27 04:00:00 EDT 1987 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100302a034· OSTI ID:5916043

Lyman, J L; Holland, R

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.

• Research Organization: Los Alamos National Lab., NM
• OSTI ID: 5916043
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 91:18; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400500 -- Photochemistry
400702* -- Radiochemistry & Nuclear Chemistry-- Properties of Radioactive Materials
ACTINIDE COMPOUNDS
CHEMICAL PREPARATION
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
DATA
DECOMPOSITION
ELEMENTS
EXPERIMENTAL DATA
FLUORIDES
FLUORINE
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
HALOGENS
INFORMATION
KINETICS
LASERS
MEDIUM TEMPERATURE
MONOMERS
NONMETALS
NUMERICAL DATA
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
POLYMERS
QUANTITY RATIO
REACTION KINETICS
SYNTHESIS
TIME DEPENDENCE
URANIUM COMPOUNDS
URANIUM FLUORIDES
URANIUM PENTAFLUORIDE