Spin Diffusion in 3He, Adsorbed Nanostructured Material MCM-41

The pulsed nuclear magnetic resonance method was used for the first time to study diffusion processes in He-3, adsorbed nanostructured material MCM-41. The material contained bundles of nanotubes with internal cylindrical channels whose diameter was 2.5 nm. The measurements were made using the Hahn-Carr-Purcell spin echo method with a sequence of 90 degrees-tau-180 degrees probing pulses, where tau is the time interval between pulses. Two different diffusion processes were detected in the system, with diffusion coefficients differing by an order of magnitude. This result was confirmed by an independent multi-echo method with a pair of 90 degrees-tau-120 degrees probing pulses, and with a noticeable increase in the duration of the pulses themselves. It was also found that both diffusion coefficients depend on the value of tau, which is a characteristic feature of restricted diffusion. The results obtained set new directions for the further study of this system. Published by AIP Publishing.