MAGNETIC-FIELD EFFECT IN THE GEMINATE RECOMBINATION OF RADICAL-ION PAIRS - POSSIBLE PITFALLS IN MICROSECOND MEASUREMENTS OF TRIPLET REACTION-PRODUCTS

In the geminate recombination reaction of radical ion pairs with overa ll triplet multiplicity, locally excited triplet molecules are generat ed. The magnetic field effect (of the hyperfine type) on the triplet y ield is usually determined by measuring the triplet absorbance both at zero and at higher applied magnetic fields. It is shown that the magn itude of this magnetic field effect decreases with time if the decay o f the triplet concentration measured in the microsecond range is not o f first order. This has been demonstrated experimentally using the lin ked acceptor-donor compound pyrene-(CH2)16-DMA as the test molecule in acetonitrile.