n-pentane and Isopentane in One-Dimensional Channels

Shreyas, Y and Bhide, Y and Yashonath, S (2003) n-pentane and Isopentane in One-Dimensional Channels. In: Journal of the American Chemical Society, 125 (24). pp. 7425-7434.

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Abstract

Molecular dynamics studies of n-pentane and isopentane in one-dimensional channels of $AlPO_{4}-5$ and a carbon nanotube are reported. Variation of the structure and energetics in $AlPO_{4}-5$ along the channel axis of isopentane is similar to what has been found for other rigid molecular systems. In n-pentane, these properties exhibit more frequent undulations along the channel due to flexibility. The end-to-end distance of n-pentane is a function of its position along the channel in $AlPO_{4}-5$, suggesting that n-pentane has to alternately stretch in the narrow part and destretch or coil in the broader part of the channel. n-Pentane lies flat instead of upright on the inner surface of the carbon nanotube. Both of the species exhibit diffusive motion in $AlPO_{4}-5$, and the self-diffusivity is higher than that in bulk. Isopentane has a higher diffusivity than does n-pentane. This is attributed to the higher cross section of isopentane, which is closer to the void cross section. Further, the coupling of the translational motion with the slower dihedral angle reorientation in the case of n-pentane decreases its mobility. Superdiffusive motion is seen for both species in the carbon nanotube. These results can be understood in terms of the levitation effect.

Item Type:	Journal Article
Publication:	Journal of the American Chemical Society
Publisher:	American Chemical Society
Additional Information:	Copyright of this article belongs to American Chemical Society.
Department/Centre:	Division of Interdisciplinary Sciences > Supercomputer Education & Research Centre Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	16 May 2007
Last Modified:	19 Sep 2010 04:37
URI:	http://eprints.iisc.ac.in/id/eprint/10882

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