Show simple item record

dc.contributor.authorSinger, P.M.
Asthagiri, D.
Chapman, W.G.
Hirasaki, G.J.
dc.date.accessioned 2018-09-11T20:40:46Z
dc.date.available 2018-09-11T20:40:46Z
dc.date.issued 2018
dc.identifier.citation Singer, P.M., Asthagiri, D., Chapman, W.G., et al.. "NMR spin-rotation relaxation and diffusion of methane." The Journal of Chemical Physics, 148, (2018) AIP: https://doi.org/10.1063/1.5027097.
dc.identifier.urihttps://hdl.handle.net/1911/102502
dc.description.abstract The translational diffusion-coefficient and the spin-rotation contribution to the 1H NMR relaxation rate for methane (CH4) are investigated using MD (molecular dynamics) simulations, over a wide range of densities and temperatures, spanning the liquid, supercritical, and gas phases. The simulated diffusion-coefficients agree well with measurements, without any adjustable parameters in the interpretation of the simulations. A minimization technique is developed to compute the angular velocity for non-rigid spherical molecules, which is used to simulate the autocorrelation function for spin-rotation interactions. With increasing diffusivity, the autocorrelation function shows increasing deviations from the single-exponential decay predicted by the Langevin theory for rigid spheres, and the deviations are quantified using inverse Laplace transforms. The 1H spin-rotation relaxation rate derived from the autocorrelation function using the “kinetic model” agrees well with measurements in the supercritical/gas phase, while the relaxation rate derived using the “diffusion model” agrees well with measurements in the liquid phase. 1H spin-rotation relaxation is shown to dominate over the MD-simulated 1H-1H dipole-dipole relaxation at high diffusivity, while the opposite is found at low diffusivity. At high diffusivity, the simulated spin-rotation correlation time agrees with the kinetic collision time for gases, which is used to derive a new expression for 1H spin-rotation relaxation, without any adjustable parameters.
dc.language.iso eng
dc.publisher AIP
dc.rights Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
dc.title NMR spin-rotation relaxation and diffusion of methane
dc.type Journal article
dc.citation.journalTitle The Journal of Chemical Physics
dc.citation.volumeNumber 148
dc.type.dcmi Text
dc.identifier.doihttps://doi.org/10.1063/1.5027097
dc.identifier.pmid 29865803
dc.type.publication publisher version
dc.citation.articleNumber 204504


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record