Anisotropic proton hyperfine interaction in the electron spin resonance spectrum of the ethyl radical

Abstract

The ESR spectrum of the ethyl radical isolated in an argon matrix at 4.2°K has been measured. The radical was produced by the photolysis of a mixture of C2H4 and HI with radiation from a high-pressure mercury lamp. From a line-shape analysis of the observed spectrum, the following anisotropic hyperfine interaction parameters for the α and β protons, and g values have been obtained: A⊥α=19.4± 0.5 G, A∥α=29.6± 0.5 G, A⊥β=25.9± 0.5 G, A∥β=28.7± 0.5 G, gav=2.0023± 0.0003 (Δ g= g∥ − g⊥ ≤ 0.0003). These ESR parameters provide the first experimental assessment of currently available theoretical results on the proton hyperfine anisotropy in C2H5.