Study of self-diffusion in dense hydrogen gas by quasielastic incoherent neutron scattering

Self-Diffusion in Molecular Fluids and Noble Gases: Available Data

“…In fact, neutron scattering is a technique that needs the self-diffusion coefficients to validate theories and approximations. The normal procedure when dealing with it is to assign mathematical expressions to all parts of eq and to the coherent contribution, if necessary, and then (i) to obtain 11 and other fitting parameters from the experimental spectrum and to compare the calculated self-diffusion coefficients with those available in the literature, ,− or (ii) to take diffusivities from the literature, to solve eq and to compare the calculated S ( Q⃗ ,ω) with the experimental one. − Therefore, in the Supporting Information, we have only included the aforementioned hydrogen of Chen et al…”

“…In the case of carbon tetrafluoride, where only two sets of supercritical points are available, it is not possible to know which are correct, since those of Khoury and Kobayashi 284 are systematically (20 to 40) % lower than those of Has and Ludemann. 291 For hydrogen, the neutron scattering 551 produced results (5 to 10) % higher than the spin−echo technique, 419 the former being in better agreement with the low-density tracer diffusivities than the latter.…”

“…This was the procedure followed by Chen et al 551 to determine the self-diffusion of supercritical hydrogen at (78 and 293) K and pressures from (13.2 to 197.2) MPa with an accuracy of 10 %.…”

“…ASSOCIATED CONTENT * S Supporting InformationThe Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jced.5b00323.Properties of the considered substances and all the data of Tables 1,2,4, and 5, together with the points obtained by Chen et al551 for hydrogen through neutron scattering (ZIP)■ AUTHOR INFORMATIONCorresponding Author *E-mail: medina@uniovi.es.…”

Atomically Smooth Stress-Corrosion Cleavage of a Hydrogen-Implanted Crystal

“…This can be assumed to be spatially homogeneous at all times due to the high diffusivity of H 2 inside the platelet. In particular, the H 2 selfdiffusion coefficient is a few orders of magnitude larger than the diffusion coefficient of H in crystalline Si [34]. If we define an ''active'' distance from the HIP edges within which H 2 molecules can spontaneously dissociate (typically taken to be the sum of the Si and H covalent radii), we find that, as r grows by successive stresscorrosive events, its time derivative can be expressed by _ r ¼ ð À1 Þ (derived in Ref.…”