Time-domain EPR study of the SO/sup -//sub 3/ combination reaction: Radical pair CIDEP without singlet--triplet mixing
The radical ion xSO/sup -//sub 3/ was studied by in situ pulsed radiolysis of aqueous alkaline sodium sulfite solutions in a pulsed EPR spectrometer. Initial radical concentrations on the order of 5 x 10/sup -4/ M were generated, and detailed measurements of the decay of xSO/sup -//sub 3/ magnetization were performed on the microsecond time scale. It was found that the second order decay of both longitudinal and transverse magnetization lags behind the second order decay of radical population when the reaction rate approaches the relaxation rates 1/T/sub 1,2/. The observations may be explained in terms of the spin-pairing requirements for formation of a singlet reaction product. The spin pairing gives rise to a ''passive'' form of radical pair mechanism (RPM) chemically induced dynamic electron polarization (CIDEP) which has previously gone unrecognized. RPM polarization therefore occurs in xSO/sup -//sub 3/ encounters despite the lack of hyperfine dependent singlet--triplet mixing between radical reencounters, which is necessary for the accepted RPM mechanism. The implications of these observations for the interpretation of time-resolved EPR experiments are discussed.
- Research Organization:
- Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439
- DOE Contract Number:
- W-31-109-ENG-38; AC02-82ER12042
- OSTI ID:
- 6948134
- Journal Information:
- J. Chem. Phys.; (United States), Vol. 86:9
- Country of Publication:
- United States
- Language:
- English
Similar Records
FT-EPR study of the photochemical homolysis of Re- and Ru-alkyl bonds in Re(R)(CO){sub 3}({alpha}-diimine) and Ru(I)(R)(CO){sub 2}({alpha}-diimine) complexes. Evidence for the reactive {sigma}(M-R){pi}{sup *} state
H/D isotope effects in water radiolysis. 1. Chemically induced dynamic electron polarization of spurs
Related Subjects
AQUEOUS SOLUTIONS
RADIOLYSIS
SODIUM COMPOUNDS
SULFITES
CHEMICAL REACTIONS
ELECTRON SPIN RESONANCE
ION PAIRS
MOLECULAR IONS
POLARIZATION
RADICALS
RECOMBINATION
SPIN
ALKALI METAL COMPOUNDS
ANGULAR MOMENTUM
CHARGED PARTICLES
CHEMICAL RADIATION EFFECTS
CHEMISTRY
DECOMPOSITION
DISPERSIONS
IONS
MAGNETIC RESONANCE
MIXTURES
OXYGEN COMPOUNDS
PARTICLE PROPERTIES
RADIATION CHEMISTRY
RADIATION EFFECTS
RESONANCE
SOLUTIONS
SULFUR COMPOUNDS
400600* - Radiation Chemistry