The Formation of Pairs of Widely Spaced Methyl Radicals following Fluorine Photolysis in Solid Methane at 10–15 K

Quantum yields of CH₃ radicals (Y_R = 0.95±0.2) and CH₃F…F complexes (Yo = 0.6±0.1), formed by UV photolysis in CH₄–F₂ solid mixtures (70:1), have been measured using EPR and IR spectroscopy. Since 12YR+Y0≅1, fluorine atoms do not recombine in a cage; approximately half of them are involved in formation of the complexes while the rest gives CH₃ radical pairs. The fraction of pairs with an inter-radical spacing >20 Å is 0.1–0.15.