Observation of a solid phase under measuring the 3He diffusion coefficient in the nanopores of the MCM-41 adsorbent
Observation of a solid phase under measuring the 3He diffusion coefficient in the nanopores of the MCM-41 adsorbent
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DOI：
10.1063/10.0012646
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发表时间：
2022-08-01
影响因子：
0.8
通讯作者：
Sopelnyk, Ya. Yu.
中科院分区：
文献类型：
--
作者：
Birchenko, A. P.;Maidanov, V. A.;Sopelnyk, Ya. Yu.
利用核磁共振技术，采用受激自旋回波法测量了新一代纳米结构吸附剂MCM-41的圆柱形孔道（孔道直径为25 ANGS）中He-3单分子层的扩散系数。氦气以小部分进入样品中，这使得可以以受控的方式改变吸附剂中空腔壁的覆盖率。它被发现，所测得的受激自旋回波幅度的磁场梯度的平方的依赖性是指数。这种依赖性的性质使得有可能确定在吸附的单层的扩散系数。结果表明，该扩散系数的值接近于氦在固体中的扩散系数，表明圆柱形腔体内表面的He-3第一单分子层是固体。当计算由于吸附物质的货车范德华力而作用在氦单层上的压力时，该结论得到了证实。由AIP Publishing独家授权出版。
Using nuclear magnetic resonance, the stimulated spin-echo method was applied to measure the diffusion coefficient in a He-3 monolayer adsorbed inside cylindrical pores (channel diameter 25 & ANGS;) of a new-generation nanostructured adsorbent MCM-41. Helium was let into the sample in small portions, which made it possible to change in a controlled way the coverage of the walls of the cavities in the adsorbent. It is found that the measured dependence of the stimulated spin-echo amplitude on the square of the magnetic field gradient is exponential. The nature of this dependence made it possible to determine the diffusion coefficient in the adsorbed monolayer. The value of this coefficient turned out to be close to the diffusion coefficient in solid helium, which indicates that the first He-3 monolayer on the inner surface of the cylindrical cavity is solid. This conclusion was confirmed when calculating the pressure acting on the helium monolayer due to the van der Waals forces from the adsorbent substance. Published under an exclusive license by AIP Publishing.