Electron spin relaxation and rotational dynamics of tetramethylethylene radical cation in ZSM5

Electron spin relaxation and methyl rotation dynamics of the tetramethylethylene radical cation in ZSM5 were examined to probe the zeolite–guest and sorbate–sorbate interactions. T1 and T2 relaxation times and the intensity of the E lines due to tunneling rotation of methyl groups were measured as a function of temperature, sorbate loading and co-adsorbed argon. The EPR results demonstrate that site heterogeneity and sorbate-induced lattice distortions can affect the measured quantities. Sorbate–sorbate interactions, when they occur, can also be detected.