Positronium formation process in organic liquids

Journal Article · Thu Nov 02 04:00:00 EST 1978 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100511a006· OSTI ID:6513680

Djermouni, B; Ache, H J

The formation of positronium in benzene solutions containing a variety of halogenated compounds, such as CCl/sub 4/, CH/sub 2/Cl/sub 2/, C/sub 2/HCl/sub 3/, 1,1,1-C/sub 2/H/sub 3/Cl/sub 3/, o-C/sub 6/H/sub 4/CH/sub 3/Br, o-C/sub 6/H/sub 4/Cl/sub 2/, o-C/sub 6/H/sub 4/CH/sub 3/Cl, C/sub 6/H/sub 5/Cl, and other mono- and dihalobenzene, was studied in the presence and absence of C/sub 6/F/sub 6/ additives. The observed I/sub 2/ values, which are indicative of the number of thermalized positronium atoms formed, showed in each system a good correlation with dissociative electron attachment parameters of the solute species. C/sub 6/F/sub 6/ additives increased the number of Ps atoms reaching thermal energies. The experimental results are discussed in terms of a reaction scheme in which Ps is formed as a result of electron abstraction from the surrounding molecules by energetic positrons. These Ps atoms can either react rapidly with solute species if their excess kinetic energy favors such a reaction, or with species generated in the reactions of free electrons produced in the positron spur with solute molecules via dissociative electron attachment. The number of these reactive species is mainly determined by the number of free electrons having sufficient energies to undergo dissociative electron attachment. A compound such as C/sub 6/F/sub 6/, which has a high cross section for nondissociative electron attachment, competes for free electrons with the solute, and protects the latter from radiolysis. Thus in the presence of C/sub 6/F/sub 6/ fewer reactive species are formed in the spur with which the Ps can rapidly react and more Ps atoms will reachthermal energies. An alternative to this reaction scheme is the previously reported spur reaction model which assumes positronium formation via free positron and free electron combination in the positron spur. The results will be also discussed within the framework of this latter model. 12 figures, 1 table.

• Research Organization: Virginia Polytechnic Inst. and State Univ., Blacksburg
• OSTI ID: 6513680
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 82:22; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400702* -- Radiochemistry & Nuclear Chemistry-- Properties of Radioactive Materials
ACTIVATION ENERGY
ADDITIVES
ALKALI METAL ISOTOPES
ALKANES
AROMATICS
BENZENE
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
BROMINATED AROMATIC HYDROCARBONS
CARBON TETRACHLORIDE
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
CHEMISTRY
CHLORINATED ALIPHATIC HYDROCARBONS
CHLORINATED AROMATIC HYDROCARBONS
CROSS SECTIONS
CYCLOALKANES
CYCLOHEXANE
DECOMPOSITION
DISSOCIATION ENERGY
ELECTROMAGNETIC RADIATION
ELECTRON ATTACHMENT
ELECTRONS
ELEMENTARY PARTICLES
ENERGY
FERMIONS
FLUORINATED AROMATIC HYDROCARBONS
GAMMA RADIATION
HALOGENATED ALIPHATIC HYDROCARBONS
HALOGENATED AROMATIC HYDROCARBONS
HYDROCARBONS
IONIZING RADIATIONS
ISOTOPES
KINETICS
LEPTONS
LIGHT NUCLEI
NUCLEI
ODD-ODD NUCLEI
ORGANIC BROMINE COMPOUNDS
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC SOLVENTS
PARTICLE SOURCES
POSITRON SOURCES
POSITRONIUM
QUANTITY RATIO
RADIATION CHEMISTRY
RADIATION EFFECTS
RADIATION SOURCES
RADIATIONS
RADIOISOTOPES
RADIOLYSIS
REACTION KINETICS
SODIUM 22
SODIUM ISOTOPES
SOLVENTS
TIME DEPENDENCE
YEARS LIVING RADIOISOTOPES
YIELDS