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

The hyperfine induced magnetic field effect on N,N,N′,N′-tetramethylparaphenylenediamine (TMPD) cation-geminate electron recombination fluorescence is reported as a function of temperature in squalane. Magnetic field effects were additionally observed over some limited temperature range in the liquid, supercooled liquid and solid states of some smaller saturated hydrocarbons. The temperature dependence of the magnetic field effect intensity in squalane 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 diffusion and tunneling in the Coulomb field.