Magnetic interaction between copper (II) ion and paramagnetic NO and O2 molecules in Y-type zeolite at low temperature: An EPR study

Electron paramagnetic resonance (EPR) spectra of partially copper ion exchanged Na-Y zeolite (CuNa-FAU) were measured in the presence of paramagnetic gases such as nitrogen monoxide (NO) and oxygen (O2) as a function of temperature (110-270 K). The EPR signal intensities of the Cu2+ ions deviated from those predicted by Curie's paramagnetic law due to the magnetic interaction between the Cu2+ ions and paramagnetic gaseous molecules adsorbed on the zeolites; the minimum signal intensity was observed at 150-170 K for CuNa-FAU with NO and the maximum intensity was observed at 170-190 K for CuNa-FAU with O2. The temperature dependent signal intensities, accompanying the NO adsorption, were discussed in terms of the Langmuir adsorption model in the higher temperature range of 150-190 K.