Stimulated echo and diffusion processes in 3He adsorbed by MCM-41 nanostructured material.

Autor: Birchenko, A. P., Mikhin, N. P., Rudavsky, E. Ya., Sopelnyk, Ya. Yu.
Předmět:
Zdroj: Low Temperature Physics; Dec2019, Vol. 45 Issue 12, p1237-1240, 4p, 4 Graphs
Abstrakt: The diffusion processes in 3He adsorbed by MCM-41 nanostructured material with a channel diameter of 2.5 nm were studied using pulsed nuclear magnetic resonance. The measurements were carried out using the stimulated spin echo method with a three-pulse spin system excitation regime. The measured dependences of the stimulated spin echo amplitude on the square of the magnetic field gradient showed the presence of two different slopes along the curve, which means the presence of two different diffusion processes in the adsorbed helium. These processes correspond to two different layered phases that are formed during the gas adsorption in a narrow channel, due to the van der Waals interaction with the walls. These phases were identified according to the measured values of the diffusion coefficient. It turned out that one of the layered phases corresponds to gaseous helium, and the other phase is close to liquid helium. The utilized methods did not allow for the detection of the solid phase, which is usually formed in a narrow parietal layer. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index