Abstract
The NMR chemical shift of 129Xe adsorbed on zeolites is very large and sensitive to the environment of xenon used as a probe. Among the results obtained, the most important show that the average number of atoms per particle of metal supported on zeolite is always below 10, whereas electron microscopy showed that the particle size is ca 10A. There therefore appear to be very small metal particles not detected by electron microscopy. This technique is also useful to study the adsorbate distribution and to follow step by step certain simple reactions at the surface of these metals.