D-Labelled Methyl Radicals Nuclear Spin-Rotation Couplings

1 D-Labelled Methyl Radicals Nuclear Spin-Rotation Couplings 

The methyl radical has attracted much attention since it is the most simple and fundamentally important alkyl radical. ESR spectra have been observed for methyl radicals generated in liquids [36c], isolated in inert gas matrices [46, 75], adsorbed on 

Temperature-dependent ESR spectra of the CH3 radical generated by X-ray irradiation of Ar matrix containing 0.2 mol% CH4 at 4.2 K. The spectra were recorded at (a) 6 K, (b) 

Only the /r/quartet due to 7 = 3/2 (Aj lines) is visible at 6 K. The doublet due to 7 = 1/2 E lines) marked as a star ( ) increases in intensity with increasing temperature. Because of the high resolution spectra the A1 and E lines are resolved by a small second-order shift (0.024 mT) of the H hf splitting. The figure is adapted from [75] with permission from the American Chemical Society 

Applying the Pauli principle the observed 1 1 1 1 quartet of CH3 is attributable to the four totally symmetric A nuclear spin states coupled with the rotational ground state, / = 0 (even), in the D3 symmetry (point group) [13, 75, 85]  

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