Temperature dependence of the electron spin resonance spectrum of the ClO3 radical trapped in γ-irradiated barium perhclorate

Abstract

The e.s.r. parameters of the ClO₃ radical trapped in γ-irradiated Ba(ClO₄)₂·3H₂O crystals at 298 K are g_∥= 2.0043, g_⊥= 2.0071, A_∥= 441 MHz and A_⊥= 324 MHz. The quadrupole coupling is too small to be determined precisely from the positions of the strongly allowed transitions: the parallel component is < 10 MHz. The e.s.r. parameters are temperature-dependent and have been studied throughout the range 11–313 K. The data cannot be interpreted satisfactorily using ‘isolated-molecule’ models, and it is suggested that the temperature dependence reflects the way in which the environment of the radical in the crystal constrains its vibrational potential.