Spin diffusion in 3He adsorbed by the nanostructured material MSM-41
A.P. Birchenko, N.P. Mikhin, E.Ya. Rudavskii, and Ya.Yu. Fysun
B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine 47 Nauky Ave., Kharkiv 61103, Ukraine
Received February 28, 2018
The pulsed nuclear magnetic resonance method was used for the first time to study diffusion processes in 3He adsorbed by the nanostructured material MCM-41. The material contained bundles of nanotubes with internal cylindrical channels 2.5 nm in diameter. For measurements, the Hahn–Karr–Purcell spin echo method was used with a sequence of sounding radio pulses of 90°–τ–180°, where τ is the time interval between pulses. It was found that there are two different diffusion processes in the system, in which the diffusion coefficients differ by an order of magnitude. This result was confirmed by using 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 that is a characteristic feature of restricted diffusion. It is noted that the results obtained stimulate the setting of new tasks for the further study of this system.
PACS: 67.30.-n 3He;
Key words: adsorbed helium, NMR, nanostructured material, MCM-41, diffusion.
Published online: June 27, 2018