QUANTUM BEATS IN THE RECOMBINATION FLUORESCENCE OF RADICAL-ION PAIRS CAUSED BY THE HYPERFINE COUPLING IN RADICAL-ANIONS

The ratios of the radiofluorescence decay curves for n-decane solution s of 1,2,3,4-tetraphenylcyclopenta-1,3-diene and its silicon and germa nium analogs (siloles and germoles) in high and zero magnetic fields h ave an oscillating component caused by singlet-triplet evolution of th e pair S+/A(-), where S+ is the solvent hole and A(-) is the radical a nion of the acceptor (a compound added), It is shown that the beats ar e due to the hyperfine couplings (hfc) with either the protons of CH2, SiH2 and GeH2 moieties or chlorine atoms in the GeCl2 and GeClMe moie ties of radical anions. The hfc constants in the anions and spin relax ation times of radical ion pairs were obtained by fitting the experime ntal curves. (C) 1998 Published by Elsevier Science B.V. All rights re served.