Electron hopping and magnetic field dependent spin dynamics of radical ions in solution

• Published in: Chemical physics 1983-01, Vol.74 (2), p.205-216
• Main Authors: Krüger, H.W., Michel-Beyerle, M.E., Knapp, E.W.
• Format: Article
• Language: English
• Subjects: Chemistry; Exact sciences and technology; Free radicals chemistry; Organic chemistry; Reactivity and mechanisms
• ISSN: 0301-0104
• DOI: 10.1016/0301-0104(83)80023-8

The role of hopping on the geminate recombination of radical ions (N,N-dimethylaniline cation and anthracene anion) in acetonitrile is studied via the nanosecond time-resolved magnetic field effect on the triplet yield and the influence of donor concentration thereon. Increasing donor concentration leads to lifetime broadening of the magnetic field dependence of the triplet yield. Responsible for this effect is the perturbation of the coherent spin motion caused by hopping of the electron spin between donor sites of different nuclear spin configuration. Comparison of experimental results with calculations based on the semiclassical theory of spin motion yields an estimate of the hopping rates. Deuteration of both radicals influences the halfwidth of the magnetic field effect: at long probing times and low donor concentrations the halfwidth measured for protonated radical ions exceeds the one for the deuterated species: at short delay times and large donor concentrations, i.e. high hopping rates, this isotopic effect is reversed.