Description:
The effects of 27Al (I=5/2) nuclear quadrupole interaction on the electron spin echo modulation (ESEM) in the case of S=1/2 in disordered systems are analyzed using exact diagonalization of the spin Hamiltonian. The Hamiltonian parameters used in the calculations are those expected in Cu+2-exchanged zeolites. The g anisotropy is taken into account and the ESEM obtained using the spherical model approximation is compared with a trigonal correlated structure. It is found that in the 0.32–0.34 nm range of distances between the paramagnetic center and the Al nuclei all parameters related to the quadrupole tensor, namely the quadrupole interaction constant, the asymmetry parameter and the relative orientation with respect to the g tensor, have a substantial effect on the modulation depth.