Reactions of photogenerated fluorine atoms with contaminant molecules trapped in solid argon 5. EPR spectroscopy of FC60 • radical in solid argon

Reactions of photogenerated fluorine atoms with C60 fullerene molecules isolated in solid argon were studied by EPR spectroscopy in the temperature range from 15 to 25 K. Highly resolved anisotropic EPR spectrum of the FC60⋅ radical was obtained for the first time. The spectrum is characterized by low anisotropy of the g-tensor and by axially symmetric HFC tensor on 19F nuclei. The parameters of the HFC tensor for 19F magnetic nuclei were determined. The isotropic HFC constant Aiso equals 202.8 MHz and the anisotropic magnetic dipole-dipole interaction constant Adip equals 51.8 MHz. Quantum chemical calculations of FC60⋅ radical showed that the PBE1/Λ22m method (PBE1 functional and the correlation triple-zeta basis sets augmented with polarization functions on inner atomic shells) provides good agreement between the theoretical magnetic parameters and experimental data. Specific features of the spin density distribution in the FC60⋅ radical are discussed.