Tetrameric silver clusters in rho zeolite stable above room temperature - ESR studies

Cationic silver clusters formed in gamma-irradiated Ag+-exchanged zeolite rho have been studied by electron spin resonance (ESR) spectroscopy. It was found that dehydrated Ag-rho zeolites show a remarkable tendency for stabilization of Ag-4(3+) clusters. In dehydrated samples tetrameric silver is stable for months at room temperature and is still observed at 100 degrees C. It is postulated that Ag-4(3+) clusters are located in distorted octagonal prisms which appear to be very effective trapping sites. In hydrated rho zeolite framework distortions are removed and silver tetramers decay below room temperature.