The cyclohexadienyl radical

  • E. Roduner
Part of the Lecture Notes in Chemistry book series (LNC, volume 49)


The cyclohexadienyl radical, C6H7, was often observed by ESR of irradiated benzene [45,23]. Similarly, C6D6H was detected upon X-irradiation of benzene-d6 in adamantane [46]. The muonated analogues, C6H6Mu and C6D6Mu, were among the first organic radicals detected by μSR [8,47]. Corresponding FT-μSR spectra are shown for different magnetic fields in Figure 4.1. Only the radical lines are displayed. As in all μSR spectra of organic liquids, there is a further strong line at a low frequency corresponding to ω D for muons in diamagnetic environments. As a function of field the radical lines behave as described in Table 3.2 and on page 23. They are placed symmetrically around \( \frac{1}{2}{A_{\mu }} \) (broken line). In high fields, here 3000 G, there are two lines. The sum of the two frequencies gives the muon-electron hyperfine coupling constant directly. We obtain Aμ = 514.6 MHz for C6H6Mu and Aμ = 520.0 MHz for C6D6Mu, which corresponds to reduced coupling constants
$$ A_{\mu }^{'} = {A_{\mu }} \cdot {\mu _{p}}/{\mu _{\mu }} = 0.3142 \cdot {A_{\mu }} $$
of 161.7 MHz and 163.4 MHz, respectively. At 1000 G the lines of C6H6Mu split into doublets by 1.23 MHz, which is slightly less than in a less accurate early determination [26]. The splitting increases to 2.5 MHz at 700 G and 4.9 MHz at 500 G. Based on perturbation treatment (page 23) this corresponds to about 150 MHz for the coupling constant of a proton. Accurate numerical.


Hyperfine Coupling Radical Line Hyperfine Coupling Constant Muon Polarization Pure Benzene 
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© Springer-Verlag Berlin Heidelberg 1988

Authors and Affiliations

  • E. Roduner
    • 1
  1. 1.Physikalisch-Chemisches InstitutUniversität ZürichZürichSwitzerland

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