One electron transfer equilibria and redox potentials of radicals studies by pulse radiolysis. Progress report, September 1, 1975--July 1, 1976. [Electron beams and gamma rays]

Technical Report · Thu Jan 01 04:00:00 EST 1976

OSTI ID:7156672

Meisel, D; Czapski, G

The pulse radiolysis technique is utilized for measurements of the equilibrium constants for electron transfer between the durosemiquinone radical anion and oxygen, menadione and indigo disulfonate. These equilibrium constants are in turn used for calculations of one-electron redox potentials for these systems. Each of these equilibrium constants was determined experimentally and independently and found to be self consistent. Only for the reactions of the semiquinones with oxygen could the electron transfer reaction be followed directly. For the reactions between the various quinone/semiquinone systems substantial indirect evidence is presented that these equilibria are achieved rapidly. In those cases equilibrium constants were determined from studies of the effect of quinone concentrations on the relative yields of the semiquinones. A method for distinguishing between kinetic competition and equilibrium is outlined and its usefulness is emphasized. The DQ/DQ/sup -/ (DQ = duroquinone) and IDS/IDS/sup -/ (IDS = indigo disulfonate) systems were employed as reference couples as the redox potentials for those systems are either available in the literature (IDS/IDS/sup -/) or may be calculated from available data (DQ/DQ/sup -/). Taking E/sub 7//sup 1/, the redox potential for the first one-electron reduction step at pH 7, of DQ/DQ/sup -/ as -0.235 volts or of IDS/IDS/sup -/ as -0.125 volts, both yield E/sub 7//sup 1/ = -0.325 V for the O/sub 2//O/sub 2//sup -/ system (1 atm O/sub 2/) and E/sub 7//sup 1/ = -0.20 for the menadione system.

• Research Organization: Carnegie-Mellon Univ., Pittsburgh, Pa. (USA); Hebrew Univ., Jerusalem (Israel)
• OSTI ID: 7156672
• Report Number(s): COO-3221-38
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400600* -- Radiation Chemistry
AROMATICS
BEAMS
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTIONS
CHEMISTRY
DECOMPOSITION
ELECTROMAGNETIC RADIATION
ELECTRON BEAMS
ELECTRON TRANSFER
ENERGY RANGE
GAMMA RADIATION
IONIZING RADIATIONS
IRRADIATION
LEPTON BEAMS
MEV RANGE
MEV RANGE 01-10
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PARTICLE BEAMS
PULSED IRRADIATION
QUINONES
RADIATION CHEMISTRY
RADIATION EFFECTS
RADIATIONS
RADICALS
RADIOLYSIS
REDOX POTENTIAL
RESEARCH PROGRAMS