Quasielastic neutron scattering of -NH3 and -BH3 rotational dynamics in orthorhombic ammonia borane

Nancy J. Hess; Michael R. Hartman; Craig M. Brown; Eugene Mamontov; Abhijeet Karkamkar; David J. Heldebrant; Luc L. Daemen; Tom Autrey

doi:10.1016/j.cplett.2008.04.130

Quasielastic neutron scattering of -NH₃ and -BH₃ rotational dynamics in orthorhombic ammonia borane

Nancy J. Hess, Michael R. Hartman, Craig M. Brown, Eugene Mamontov, Abhijeet Karkamkar, David J. Heldebrant, Luc L. Daemen, Tom Autrey

Research output: Contribution to journal › Article › peer-review

28 Scopus citations

Abstract

Energy barriers for rotation of -NH₃ and -BH₃ in the orthorhombic phase of ammonia borane, NH₃BH₃, were determined using quasielastic neutron scattering (QENS). QENS confirms the 3-site jump model of rotational diffusion and yields barrier heights of 23.6 ± 1.0 kJ/mol and 14.8 ± 0.4 kJ/mol for the borane and amine groups, respectively, which are comparable to barrier heights determined by recent ²H and ¹⁵N NMR studies suggesting no significant isotope effect on rotational motion in the orthorhombic phase of ammonia borane.

Original language	English
Pages (from-to)	85-88
Number of pages	4
Journal	Chemical Physics Letters
Volume	459
Issue number	1-6
DOIs	https://doi.org/10.1016/j.cplett.2008.04.130
State	Published - Jun 27 2008
Externally published	Yes

Funding

This work was supported by the Office of Basic Energy Sciences Hydrogen Fuel Initiative, Chemical Sciences Division, of the US Department of Energy. Pacific Northwest national Laboratory is operated for the DOE by Battelle. We acknowledge the support of the National Institute of Standards and Technology, US Department of Commerce, in providing neutron research facilities. Additionally, this work utilized HFBS which is supported in part by the NSF under Agreement No. DMR-0454672. A portion of the research described in this paper was performed in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at PNNL.

Funders	Funder number
Chemical Sciences Division
Office of Basic Energy Sciences Hydrogen Fuel Initiative
National Science Foundation	DMR-0454672
U.S. Department of Energy
National Institute of Standards and Technology
U.S. Department of Commerce

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title = "Quasielastic neutron scattering of -NH3 and -BH3 rotational dynamics in orthorhombic ammonia borane",

abstract = "Energy barriers for rotation of -NH3 and -BH3 in the orthorhombic phase of ammonia borane, NH3BH3, were determined using quasielastic neutron scattering (QENS). QENS confirms the 3-site jump model of rotational diffusion and yields barrier heights of 23.6 ± 1.0 kJ/mol and 14.8 ± 0.4 kJ/mol for the borane and amine groups, respectively, which are comparable to barrier heights determined by recent 2H and 15N NMR studies suggesting no significant isotope effect on rotational motion in the orthorhombic phase of ammonia borane.",

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AU - Hess, Nancy J.

AU - Hartman, Michael R.

AU - Brown, Craig M.

AU - Mamontov, Eugene

AU - Karkamkar, Abhijeet

AU - Heldebrant, David J.

AU - Daemen, Luc L.

AU - Autrey, Tom

PY - 2008/6/27

Y1 - 2008/6/27

N2 - Energy barriers for rotation of -NH3 and -BH3 in the orthorhombic phase of ammonia borane, NH3BH3, were determined using quasielastic neutron scattering (QENS). QENS confirms the 3-site jump model of rotational diffusion and yields barrier heights of 23.6 ± 1.0 kJ/mol and 14.8 ± 0.4 kJ/mol for the borane and amine groups, respectively, which are comparable to barrier heights determined by recent 2H and 15N NMR studies suggesting no significant isotope effect on rotational motion in the orthorhombic phase of ammonia borane.

AB - Energy barriers for rotation of -NH3 and -BH3 in the orthorhombic phase of ammonia borane, NH3BH3, were determined using quasielastic neutron scattering (QENS). QENS confirms the 3-site jump model of rotational diffusion and yields barrier heights of 23.6 ± 1.0 kJ/mol and 14.8 ± 0.4 kJ/mol for the borane and amine groups, respectively, which are comparable to barrier heights determined by recent 2H and 15N NMR studies suggesting no significant isotope effect on rotational motion in the orthorhombic phase of ammonia borane.

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JO - Chemical Physics Letters

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Quasielastic neutron scattering of -NH₃ and -BH₃ rotational dynamics in orthorhombic ammonia borane

Abstract

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