Magnetic field effects on TMPD cation-electron recombination fluorescence in saturated hydrocarbons

The hyperfine induced magnetic field effect on N,N,N,N'-tetramethylparaphen ylenediamine (TMPD) cation-geminate electron recombination fluorescence is reported as a function of temperature in squalane. Magnetic field effects w ere additionally observed over some limited temperature range in the liquid , supercooled liquid and solid states of some smaller saturated hydrocarbon s. The temperature dependence of the magnetic field effect intensity in squ alane is quantitatively analyzed in terms of the fraction of recombinations occurring after spin mixing but before spin relaxation. Numerical analysis of the recombination time distribution exposes the importance of both diff usion and tunneling in the Coulomb field. (C) 2001 Elsevier Science B.V. Al l rights reserved.