Optically detected electron spin echo envelope modulation on a photoexcited triplet state in zero magnetic field -: A comparison between the zero-field and high-field limits

Electron spin echo envelope modulation (ESEEM) has been studied at zero and low magnetic fields (B less than or equal to 100 G) by means of optically detected magnetic resonance, Qualitative differences of the ESEEM effect for an electronic triplet state (S = 1) under low-field and high-field conditions are observed and discussed. They are related to the different properties of the total spin angular momentum operator (S) over cap and the hyperfine interaction at zero and high magnetic field, The novel method was applied to the photoexcited triplet state of acridine-d(9) in a fluorene-h(10) matrix. An analysis of the observed nitrogen quadrupole splitting is done by a quantitative description of the ESEEM effect in zero field. (C) 1998 Academic Press.