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

• Published in: Low temperature physics (Woodbury, N.Y.) N.Y.), 2018-08, Vol.44 (8), p.755-758
• Main Authors: Birchenko, A. P., Mikhin, N. P., Rudavskii, E. Ya, Fysun, Ya. Yu
• Format: Article
• Language: English
• Subjects: Diffusion; Nanostructured materials; NMR; Nuclear magnetic resonance
• ISSN: 1063-777X; 1090-6517
• DOI: 10.1063/1.5049154

The pulsed nuclear magnetic resonance method was used for the first time to study diffusion processes in 3He, 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°–τ–180° probing pulses, where τ 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°–τ–120° 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 τ, which is a characteristic feature of restricted diffusion. The results obtained set new directions for the further study of this system.