Reevaluation of the spectral and kinetic properties of HO/sub 2/ and O/sub 2//sup -/ free radicals
The spectra and molar absorbances of the HO/sub 2/ and O/sub 2//sup -/ free radicals have been redetermined in aqueous formate solutions by pulse and stopped-flow radiolysis as well as by /sup 60/Co gamma-ray studies. The extinction coefficients at the corresponding maxima and 23/sup 0/C are epsilon(HO/sub 2/)(225 nm) = 1400 +- 80 M/sup -1/ cm/sup -1/ and epsilon(O/sub 2//sup -/)(245 nm) = 2350 +- 120 M/sup -1/ cm/sup -1/ respectively. Reevaluation of earlier published rate data in terms of the new extinction coefficients yielded the following rate constants for the spontaneous decay of HO/sub 2/ and O/sub 2//sup -/: k(HO/sub 2/ + HO/sub 2/) = (8.60 +- 0.62) x 10/sup 5/ M/sup -1/ s/sup -1/; k(HO/sub 2/ + O/sub 2//sup -/) = (1.02 +- 0.49) x 10/sup 8/ M/sup -1/ s/sup -1/; k(HO/sub 2/ + HO/sub 2/) - < 0.35 M/sup -1/ s/sup -1/. For the equilibrium HO/sub 2/ reversible O/sub 2//sup -/ + H/sup +/ the dissociation constant is K(HO/sub 2/) = (2.05 +- 0.39) x 10/sup -5/ M or pK(HO/sub 2/) = 4.69 +- 0.08. G(O/sub 2//sup -/) has been evaluated as a function of formate concentration.
- Research Organization:
- Brookhaven National Lab., Upton, NY (USA)
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 5433830
- Report Number(s):
- BNL-23153; CONF-770882-1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400600* -- Radiation Chemistry
ABSORPTION SPECTRA
AQUEOUS SOLUTIONS
CARBOXYLIC ACID SALTS
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMISTRY
CHLORINE COMPOUNDS
DECOMPOSITION
DISPERSIONS
ELECTROMAGNETIC RADIATION
FORMATES
G VALUE
GAMMA RADIATION
HALOGEN COMPOUNDS
IONIZING RADIATIONS
KINETICS
MIXTURES
OXYGEN COMPOUNDS
PERCHLORATES
PH VALUE
RADIATION CHEMISTRY
RADIATION EFFECTS
RADIATIONS
RADICALS
RADIOLYSIS
REACTION KINETICS
SOLUTIONS
SPECTRA
SUPEROXIDE RADICALS