Triplet State EPR of Substituted Naphthalenes

Paramagnetic resonance absorption has been observed in single‐crystal solid solutions of durene and 2‐fluoronaphthalene and 2‐methylnaphthalene when irradiated at 80°K with uv light. The fine structure observed at 35 GHz is very similar to that of naphthalene except that the in‐plane $x$ and $y$ axes are rotated by 7.3° ± 0.5° and 8° ± 1° for 2‐fluoronaphthalene and 2‐methylnaphthalene, respectively. Analysis of the hyperfine spectra suggests that the molecules may not be oriented exactly along the durene axes but rotated slightly in the plane of the molecules.